Pages can be switched by:
- swiping left or right (uses page creation order);
- using the back and forward buttons at the top right of the screen (uses the page history list);
- pressing the page title (brings up the pager).
To close a page:
- to close the active page, press the Back button of your device;
- to close another page, swipe it out to the left or right screen edge in the pager.
Acid Ape Chess exits when the last remaining page is closed.
Notable Acid Ape Chess pages include:
The New Game page allows you to quickly play online or against a chess engine.
Other game types (human duel, engine duel) and options (asymmetric clocks, custom position) are available in the
play dialog.
The New Game page is displayed when Acid Ape Chess starts, and can be explicitly accessed by using Game > New in the main menu.
The color selector allows you to select the user color.
The time selector allows you to choose a time control.
By default, the selector is in custom mode, allowing you to set a specific time and Fischer increment.
Press the settings button to select more advanced time controls from the time control selection dialog.
When a player runs out of time, he usually loses the game (but not always: see autoflagging).
Online chess servers only support a simple single-period time control, with an optional Fischer increment but without a move limit.
The Chess960 button toggles the Chess960 mode. In this mode, a random Chess960 position is used for the new game.
The blindfold button toggles the blindfold mode. In this mode, the board is masked and moves must be entered via speech recognition.
The game type selector allows you to choose between different game types.
Select this tab to play a game on an online chess server.
By default, guest accounts for the three supported servers are configured. You can add more accounts (guest or authenticated) with the add toolbar button at the bottom of the screen.
The connection status of an account is displayed at the bottom right of its icon.
An opponent rating range can be selected using the bottom slider. Note that if a Lichess account is selected, this slider is only available if the account is not anonymous.
By default, an unrated game is created. To play a rated game, select an account having a username and password, then press the trophy icon at the left of the PLAY button.
Select this tab to play a game against a chess engine installed on your device.
Acid Ape Chess ships with three built-in engines. You can add more engines with the add toolbar button at the bottom of the screen.
If the selected engine supports adjustable strength, the engine strength can be selected using the bottom slider.
If the selected engine supports personalities, a personality selector is displayed instead of the strength slider. At the time of this writing, one such engine (Rodent III) can be found in our separate Chess Engines Collection package. This package can be quickly installed using the add toolbar button.
The ELO rating at the right of each engine is updated every 24 hours from
CCRL 40/15.
Select this tab to play a simul against multiple instances of a chess engine installed on your device.
Differences with the ENGINE tab:
- the default strength is 50% (it is assumed that you will prefer weaker opponents when playing many of them);
- a boards control allows you to select the number of opponents.
The boards value defaults to a small number (smaller than most real life exhibitions) for good reasons. Since one engine instance is running per board, you might exceed your device processor and/or memory capabilities by inadvertently configuring too many boards (if your device becomes overloaded, it might freeze for long periods while trying to recover).
Press this button to create a game of the selected type or to cancel a seek in progress.
The game page allows you to play, view, analyze and edit a game.
The game page can be accessed via various parts of the app.
Most notably, from the main menu:
- an online game, engine game or simul can be created with Game > New;
- a PGN file can be opened with Game > Explorer;
- a scratch board can be created with Position > New;
- a custom game (two-player game, engine duel, asymmetric clocks, custom position, ...) can be created with Position > Play;
- a live online game can be watched with Online / OTB > Games;
- a live OTB game can be watched with Online / OTB > Relayed games;
- a recorded OTB game can be opened via Online / OTB > Players.
In the context of inter page communication, the game page is both a game data source and a game data sink.
The chessboard is obviously the central feature of Acid Ape Chess.
You can input moves using two different methods:
- press the source square, then the destination square;
- drag the piece from the source square to the destination square.
The board appearance can be modified in the board theme page.
Specific chessboard squares may be highlighted.
| Square |
Description |
 |
The square participates in an uncompleted OTB move. Complete your move. |
 |
The piece on the physical board square differs from the piece on the Acid Ape Chess board square. Fix the physical square. |
TABLE 3.7: OTB play highlighters
| Square |
Description |
 |
The source of the current puzzle hint. |
TABLE 3.8: Miscellaneous highlighters
Arrows may appear over the chessboard to highlight specific moves.
These arrows are displayed when made relevant by the current move list location.
When the
evaluation graph is enabled, the blue arrows may feature a
score gauge. Each score is computed by averaging the evaluations of the visible plots.
These arrows are displayed when a chess engine is playing the game.
In a human vs engine game, these arrows are only displayed if the
engine information subpage is currently active. In an engine duel, these arrows are always displayed.
These arrows are displayed when analysis is enabled and when the endgame tablebases online service could be queried (the board must not contain more than 7 pieces).
Cursed wins and blessed losses are mates that can be forced, but not under the fifty-move rule.
| Arrow |
Description |
 |
A legal move not yet confirmed by a clock tap. |
TABLE 3.13: OTB/OTP play arrows
| Arrow |
Description |
 |
The current premove, and the move currently being pressed in the opening explorer. |
 |
The puzzle hint. |
TABLE 3.14: Miscellaneous arrows
Some arrows may feature a score gauge.
When the Display relative eval option is enabled in the settings page, the score gauge is relative to the side to move and ranges from 0 to 400 centipawns.
When the Display relative eval option is disabled in the settings page, the score gauge is relative to white, ranges from -400 to 400 centipawns and is centered at 0.
The eval gauge displays chess engine and EGTB evaluations.
The displayed value is expressed in pawn units and clamped to the range [-4.0, +4.0].
For clarity purposes, the eval gauge ignores the
Display relative eval setting: it always displays absolute evaluations.
When analysis is in progress, the eval gauge displays the following data:
- if an EGTB result is available, that result;
- otherwise, if one of the analyzers has computed a mate, that mate;
- otherwise, the average evaluation of the participating analyzers.
Otherwise, the eval gauge averages evaluation data provided by visible subpages that are evaluation providers as follows:
- if a visible subpage has computed a mate, that mate;
- otherwise, the average evaluation of the visible subpages.
Subpages that provide evaluations are:
Finally, if no visible subpages provide evaluations and if the current move has an auto annotation, the eval gauge displays the engine evaluation contained in the annotation.
If the current position has an automatic result (checkmate, stalemate, draw by insufficient mating material, draw by fivefold repetition or draw by seventy-five-move rule), evaluation providers are not consulted: the eval gauge always displays the automatic result.
The subpage area appears at the bottom of the game page.
The tactical puzzles page allows you to open a tactical puzzle collection.
Acid Ape Chess ships with three puzzle collections of increasing difficulty, and you can import a PGN file as a custom puzzle collection.
Pressing a puzzle collection opens the puzzle collection page.
The puzzle collection page allows you to play and replay the tactical puzzles in a given puzzle collection.
Blindfold mode can be enabled with the large blindfold toggle at the left of the PLAY button.
The PGN explorer page allows you to manipulate and open PGN files stored in the Acid Ape Chess app-specific storage area.
While Android does not let you access this storage area from outside Acid Ape Chess, the PGN explorer allows you to import/export files by leveraging the system file picker.
If you uninstall
Acid Ape Chess, Android deletes the app-specific storage area containing your PGN files. It is therefore recommended that you periodically back up your games using the built-in export feature, or that you enable the
system backup.
The PGN explorer page can be accessed by using Game > Explorer in the main menu.
The PGN explorer functions like a typical mobile file manager, with first-class support for PGN files:
- a PGN file containing a single game is displayed as a normal file;
- a PGN file containing no games or more than one game is displayed as a virtual directory where each game of the PGN file is a virtual file.
This design allows you to navigate inside a PGN file and manipulate individual games as if they were files (delete them from the PGN file, copy them and so on).
To operate on a single item (game, file or directory), use its context menu by long-pressing it.
To operate on multiple items, use the Select toolbar button to enable multiple selection mode.
File operations are achieved with the cut/copy/paste file management semantics you are used to.
By default, the PGN explorer is in single selection mode (pressing an item opens it). Pressing the Select toolbar button enables multiple selection mode. Pressing it again selects all items. And again, clears the selection.
When multiple selection mode is enabled:
- pressing an item selects or deselects it;
- the multiple selection toolbar is displayed, allowing you to operate on the selected items.
The PGN explorer maintains a clipboard used for file operations.
The trash is located in Acid Ape Chess, the root location. It can be accessed with the breadcrumb.
The position editor page allows you to edit a chess position and use it for various tasks.
The position editor page can be accessed by using Position > Edit in the main menu.
In the context of inter page communication, the position editor page is both a game data source and a game data sink.
Select a piece in the bottom piece picker. This piece becomes the selected source piece.
You can now press one or more board squares to add the selected source piece to these squares.
If a square is already occupied, it is replaced by the selected source piece.
To remove a piece, first unselect the selected source piece (if any) by pressing it in the bottom piece picker, then:
- press the piece to remove;
- press the trashcan icon.
To edit the position properties (move number, castle rights, etc.), press the properties button in the page toolbar.
To toggle the side to move, press the side to move button in the page toolbar (the side to move is displayed in the page title bar).
If you edit the position in a way that makes it illegal, a red warning message is displayed at the top of the screen.
Use Game > Save in the main menu. This opens a dialog which allows you to save the position to a PGN file.
Use Position > Copy FEN to clipboard in the main menu.
Use Position > Play in the main menu. This opens the play dialog, allowing you to create an OTB, OTP or engine game from the position.
In Acid Ape Chess, this is how you can assign a chess handicap (for instance pawn odds) to one side. Edit the initial position to match the desired handicap, then create a game out of it.
The games page lists the games currently in progress on FICS and ICC.
Press a game to observe it.
The games page can be accessed by using Online / OTB > Games in the main menu.
The players page lists:
The players page can be accessed by using Online / OTB > Players in the main menu.
The OTB tab lists the players of the Acid Ape Chess game database.
The player list can be filtered by name (using the search box), by sex (using the toolbar button) and by ELO (using the slider at the bottom of the tab). The sort order can be changed using the toolbar button.
Pressing a player opens the OTB player information page.
These tabs list the online users currently connected to the respective chess server.
Pressing a user opens the user information page.
The Lichess player list is not very representative, as Lichess servers only list 50 users (seemingly chosen at random). You can however search for specific Lichess players by pressing Search for more in the toolbar of the Lichess tab.
The OTB player information page displays the data, statistics and entire official game history of a given OTB player.
Press a game to open it in a new game page.
You can conveniently search for the player on the Internet using the page toolbar.
The OTB player information page can be accessed via Online / OTB > Players in the main menu.
In some cases, it can also be accessed by pressing the name of a player in the game information subpage.
You can filter games by entering search terms in the search box, and/or by using the filter buttons in the page toolbar.
The user information page displays various information about a user connected to FICS, ICC or Lichess.
The user information page for a particular user can be accessed via Online / OTB > Players in the main menu.
In some cases, it can also be accessed by pressing the name of a player in the game information subpage.
Your own chess server profile can be accessed via Online / OTB > My profile in the main menu, or in some cases, by pressing your name in the game information subpage.
The rankings page displays:
The rankings page can be accessed by using Online / OTB > Rankings in the main menu.
The OTB tab displays the FIDE world rankings contained in the large Acid Ape Chess game database.
The player list can be filtered by name (using the search box), by sex (using the toolbar button) and by ELO (using the slider at the bottom of the tab). The sort order can be changed using the toolbar button.
Pressing a player opens the OTB player information page.
These tabs display the rankings of the respective chess server.
Pressing a user opens the user information page.
The chat page allows you to chat with other FICS and ICC users.
The chat page can be accessed by using Online / OTB > Chat in the main menu.
The chat page contains one tab per FICS/ICC chess account.
A number of standard chat channels are supported by Acid Ape Chess.
Acid Ape Chess sends chat messages using the tell FICS/ICC command.
| Channel |
Description |
| #1 |
Server help. |
| #4 |
Guest help. |
| #50 |
Registered chat. |
| #53 |
Guest chat. |
TABLE 3.27: Supported FICS channels
| Channel |
Description |
| #1 |
Server help. |
| #250 |
Lobby. |
TABLE 3.28: Supported ICC channels
The relayed games page lists OTB games relayed live by FICS.
The relayed games page can be accessed by using Online / OTB > Relayed games in the main menu.
The server notifications page displays the notifications received from FICS and ICC.
The server notifications page can be accessed by using Online / OTB > Server notifications in the main menu.
When Acid Ape Chess is connected to FICS and/or ICC, it automatically records the server notifications it receives (even if the server notifications page is not opened).
Each server notification also triggers a title bar notification, unless you disable the SHOW IN TITLE BAR toggle in the page toolbar.
Some notifications can contain action buttons. For instance, a notification about an ongoing game will usually contain a button for observing the game.
The console page allows you to use the FICS and ICC consoles.
The console page can be accessed by using Online / OTB > Console in the main menu.
The console page contains one tab per FICS/ICC chess account.
To display the server help, type help.
The settings page allows you to configure Acid Ape Chess.
The settings page can be accessed by using Settings and help > General in the main menu.
| Item |
Description |
| Sounds |
Toggle sounds. |
| Vibrations |
Toggle vibrations. |
TABLE 3.29: General settings
For usability reasons, sounds and vibrations are always enabled while the
fullscreen clock is in use.
TABLE 3.30: Board settings
TABLE 3.31: Players settings
| Item |
Description |
| Always annunciate moves |
Toggle whether to always say opponent moves |
TABLE 3.32: Speech synthesis settings
| Item |
Description |
| Default opening book |
Select a default opening book. |
| Display relative eval |
Toggle whether to display chess engine evaluations relative to the side to move. |
| Principal variations |
The number of best moves to display. |
TABLE 3.33: Chess engines settings
The
Display relative eval option does not affect
auto annotation nor the
eval gauge, both of which always use absolute evaluations (for better interoperability and readability).
The board theme page allows you to choose from a list of predefined chessboard themes and piece sets, and to toggle coordinates display.
The board theme page can be accessed by pressing the Theme button in the Board section of the settings page.
The player manager page allows you to add, remove and edit human players that will be interacting with this installation of Acid Ape Chess.
By default, your player entry is automatically added as Myself; your country is autodetected from the language settings of your device.
You can manage players with the page toolbar or the context menu of a player.
The player manager page can be accessed by pressing MANAGE PLAYERS in the Players section of the settings page.
The default player is indicated with a distinguishable star icon and can be changed by either of the following:
- selecting a player, then pressing the star icon in the toolbar;
- long-pressing a player, then pressing Set as default.
When playing on Lichess, the default player is used to supplement the following Lichess data:
- your nickname, if it is Anonymous;
- your chess title, rating, country and FIDE ID, if they are missing.
These replacements are performed locally and are only visible to yourself.
The default player is not used on FICS and ICC because they allocate a random username to guest players and have special meanings for ratings such as ++++, ---- and unreg.
When playing against a chess engine (or multiple engines in the case of a simul), the default player is used as the human side.
You might have a group of friends, colleagues or relatives with whom you are frequently playing OTB games (using a physical board) or OTP games (using OTP mode).
Adding a player entry for each group member allows for neat publication-ready data. You can for instance publish PGN files on your company intranet, or share your saved games using the game sharing feature.
It also makes for a nicer fullscreen clock or OTP display during the game.
The engine manager page allows you to add, remove or configure chess engines.
While similar functionalities are provided by the ENGINE and SIMUL tabs of the New Game page, this page might be more convenient if you have added many engines.
The engine manager page can be accessed by using Settings and help > Engines in the main menu.
The physical board page allows you to connect to a physical board and test it.
From this page, you can also:
- flip the physical clock side relative to the board (left or right);
- configure driver settings such as the stabletime delay.
The physical board page can be accessed by using Settings and help > e-Board in the main menu.
When the physical board page is opened with no physical board connected, the Bluetooth connectivity of your device is automatically enabled.
In the context of inter page communication, the physical board page is a game data source.
When no physical board is connected, the page allows you to scan for Bluetooth physical boards and connect to one.
The manual page allows you to browse the Acid Ape Chess User Manual.
The manual page can be accessed by using Settings and help > Help in the main menu.
Scroll the breadcrumb and press one of its components to navigate to the corresponding manual section.
The game subpage area contains a number of utility subpages (which may or may not be present depending on the game context).
At the top left of the subpage area, subpage management buttons can be used to alter the layout of the area.
You can move between subpages by swiping a subpage left or right, or by pressing a subpage icon at the right of the subpage title.
Pressing the subpage title toggles the subpage selector. Long-pressing the subpage title displays the subpages layout selection dialog.
Some subpages cannot be closed, while some others can usually be closed by pressing the toggle button that opened them. Consult the relevant subpage section for details.
Notable game subpages include:
This subpage provides information about the current game.
This subpage appears automatically when relevant and cannot be closed.
The game information subpage displays information and statistics about the current game.
If a player name is underlined, pressing it opens the OTB player information page or the user information page (depending on the player type).
The game information subpage is also the subpage from where you can enable the fullscreen clock and OTP mode. When relevant, FULLSCREEN CLOCK and OTP MODE buttons are present at the bottom of the subpage (on smaller screens, you might have to scroll the subpage down a bit to reach these buttons).
This subpage allows you to view or edit the move list.
This subpage appears automatically when relevant and cannot be closed.
- Variations;
- ECO display;
- Move annotations;
- Comments.
When edition mode is enabled, the move list can be edited by navigating to the appropriate node, then pressing a button in the edition toolbar.
Changes are applied to the backing file when the game is saved.
When a draw offer is made, it is recorded in the move list as (=), in accordance with the FIDE Laws of Chess rule C.12: The offer of a draw shall be marked as (=).
A draw offer is only recorded when the player proposing the draw is the side to move.
This subpage provides a visually appealing digital clock, loosely modeled after the well-known DGT3000.
This subpage appears automatically when relevant and cannot be closed.
This subpage displays the output of a chess engine.
One instance of this subpage is automatically added for each engine running in the parent game page, and is automatically removed when the engine is terminated.
This subpage displays a summary of each analyzer (a chess engine or the endgame tablebases).
To toggle analysis, use the analysis toolbar button of the game page.
This subpage is present if you have enabled it.
This subpage displays chess engine evaluations for every position in the game.
To toggle this subpage, use the evaluation graph toolbar button of the game page.
This subpage is present if you have enabled it.
- Above the graph is the plot selector: press a plot to toggle it; press the close button of a plot to remove it.
- The x-axis represents the position index (0 is the initial position).
- The y-axis represents the engine evaluation of a position, in pawn units (positive when white is winning, zero when equal, negative when black is winning).
- A red background indicates that a mate is possible in that segment of the game (if the red background is above the 0.0 line, white is mating; otherwise, black is mating).
- Red circles indicate key moves.
When an engine game is played, Acid Ape Chess records engine evaluations during the game. These plots are labeled White (engine name) or Black (engine name).
This data is saved to PGN, so it is also available when you open a previously played engine game from the PGN explorer page.
To remove a recorded plot, press the close button of that plot in the plot selector (this also removes the data from the PGN file when the game is saved).
When the game contains annotations, an Annotations plot is present.
Pressing the close button of that plot in the plot selector removes the annotations from the game. This is equivalent to selecting Game > Remove annotations in the main menu.
When you enable the subpage, Acid Ape Chess analyzes the game with the currently enabled engine analyzers. This data is cached to memory and to persistent storage; to recompute it, press the refresh button at the right of the subpage.
To add a live plot, press the add button at the right of the subpage.
To remove a live plot, press the close button of that plot in the plot selector.
The list of enabled engine analyzers is shared with analysis mode.
When an engine game is being played, live analysis only starts when the game finishes. This is to avoid depriving the game engine(s) of CPU power and to avoid overloading your device.
Red circles are placed before key moves (moves that change the engine evaluation significantly):
- small red circles indicate minor key moves, corresponding to ! or ? auto annotations;
- larger, brighter red circles indicates major key moves, corresponding to !! or ?? auto annotations.
The score indicator is displayed in the bottom left corner of the graph. It displays evaluation data for the current position, this data being collected from the visible plots. The data is in the form depth/score, depth/#mate or result, where:
- depth is the maximum search depth;
- score is the average evaluation score, in pawns (positive when white is winning, zero when equal, negative when black is winning);
- mate is the minimum number of moves to reach a mate (positive when white is winning, negative when black is winning);
- result is the automatic result (1-0 if black is checkmated; 0-1 if white is checkmated; ½-½ for a stalemate, draw by insufficient mating material, draw by fivefold repetition or draw by seventy-five-move rule).
Moreover, the score indicator displays whether the current position is a claimable draw (threefold repetition or fifty-move rule).
This subpage displays the opening moves, players and games related to the current position.
To toggle this subpage, use the opening explorer toolbar button of the game page.
This subpage is present if you have enabled it.
Tabs can be switched using the buttons at the right of the subpage.
The moves tab lists the 20 most played moves at the current position.
For each move, the following information is provided:
- the move;
- the number of games in which it was played;
- a bar chart displaying the percentage of these games that ended in a white win (white background), draw (gray background) and black win (black background).
Moves are sorted by game count in descending order.
Pressing a move plays that move.
Keeping the move entry pressed highlights the move with an arrow.
The players tab lists the 20 players that encountered the current position the most (as the side that just moved, or as white if the current position is the initial position).
For each player, the following information is provided:
- his picture, if available;
- his chess title;
- his name;
- his most recent ELO rating in the database;
- his chess federation;
- a summary of the most recent game in which he encountered the current position;
- the number of games in which he encountered the current position.
Pressing a player opens the player information page for that player.
The games tab lists the 20 most recent games in which the current position was encountered.
Pressing a game opens the game in a new game page and navigates to the current position.
This subpage allows you to chat with your opponent (using the chat facilities of the chess server the game is played on).
This subpage appears automatically when relevant and cannot be closed.
- Switch to the chat subpage.
- Press the keyboard button.
- Type your message and confirm.
Notable Acid Ape Chess dialogs include:
The time control selection dialog allows you to select from predefined and custom time controls.
The time control selection dialog can be accessed by pressing the settings button in the time selectors of the New Game page and of the play dialog.
- To select a time control, press it.
- To restore the associated time selector to the custom time/increment mode, select the Custom entry at the top of the list.
- To restore the associated time selector to the default value (usually 05.00), use the RESTORE DEFAULT button.
- To add a custom time control to the list, use the ADD button.
- To edit or remove a custom time control, access its context menu by long-pressing the entry.
Predefined time controls cannot be removed.
The play dialog allows you to create advanced chess engine games, engine duels and human duels.
While the New Game page allows you to create simple online games, engine games and simuls, the play dialog allows you to configure asymmetric clocks and use a custom initial position.
The play dialog can be accessed by using Position > Play in the main menu.
The position selector allows you to select the starting position.
| Position |
Description |
| standard |
The standard initial position. |
| Chess960 |
A randomly generated Chess960 position. |
| current (if applicable) |
The current position of the active game data source. |
| custom (if applicable) |
A non-standard initial position from a previously created game. |
TABLE 5.2: Position selector items
Each side configurator includes:
- a player selector, for selecting a human or engine player;
- if an engine which supports variable strength is selected, an engine strength selector;
- if an engine which supports personalities is selected, an engine personality selector;
- a time selector supporting simple and advanced time controls.
If the play dialog is opened when the active page is a game data source, the default values of the side configurators are taken from that game data source.
The recent games dialog lists recent settings of games created with the play dialog (from most recent to least recent). Pressing a list entry configures the play dialog with the corresponding settings.
The recent games dialog can be accessed by pressing the recent button at the bottom right of the play dialog.
The new position dialog allows you to create a scratch game page.
The new position dialog can be accessed by using Position > New in the main menu.
The position selector allows you to select the starting position.
| Position |
Description |
| standard |
The standard initial position. |
| Chess960 |
A randomly generated Chess960 position. |
| current (if applicable) |
The current position of the active game data source. |
TABLE 5.4: Position selector items
The subpages layout selection dialog allows you to save and restore multiple game subpages layouts.
The subpages layout selection dialog can be accessed by long-pressing a game subpage title.
- To add the current subpages layout to the list and close the dialog, use the ADD button.
- To apply a subpages layout to the current game page, press it.
- To remove a subpages layout, access its context menu by long-pressing the entry.
The evaluation graph settings dialog allows you to configure the evaluation graph.
The evaluation graph settings dialog can be accessed by pressing the settings button at the right of the evaluation graph.
| Item |
Description |
| Precompute graph |
If enabled, the evaluation graph is precomputed in the background while playing or viewing a game. This allows the graph plots to be available shortly after a game ends. |
TABLE 5.5: Evaluation graph settings
Enabling
Precompute graph increases CPU usage and reduces battery life. It also decreases the number of
CPU cores made available to engines during engine games. However, precomputation is inhibited when maximum engine power is required: during
analysis and during
auto annotation.
The auto annotate dialog allows you to launch automatic annotation of the current game using a chess engine, endgame tablebases and some heuristics.
The auto annotate dialog can be accessed by using Game > Auto annotate in the main menu or the auto annotate toolbar button of the game page.
| Item |
Description |
| Engine |
Select the engine used for annotation. |
| Instances |
Set the number of engine instances that should be used concurrently. |
| Time per move |
Set the search time allocated to each move. |
| Total time |
Displays the estimated total computation time, computed from Instances, Time per move and the number of moves to annotate. |
| Follow progress |
Navigate to moves as they are annotated. |
TABLE 5.6: General settings
These toggle buttons allow you to enable or disable individual output items.
| Item |
Description |
| Introduction |
Insert a PGN introduction comment before the first move. |
| Move annotation |
Add move quality annotations (!, !!, ? or ??) for moves that change the engine evaluation significantly or change the EGTB outcome. |
| Depth |
Add the engine search depth. |
| Score or mate |
Add the engine score (in pawns), or if a mate is found, the number of moves to reach it. |
| Engine best move |
Add the engine best move (if it differs from the move actually played). |
| EGTB result |
Add the EGTB result (white win, black win or draw) and best move. |
| Move comment |
Add a comment describing the quality of the move, for instance good move for the ! annotation. |
TABLE 5.7: Output settings
78... Qc4?? 34/+1.03 [Qc3] [Qc3 -> EGTB black win] bad move
| Part |
Description |
| ?? |
This black move caused a significant change in the engine evaluation. This change was profitable to white. |
| 34 |
The engine could search up to depth 34. |
| +1.03 |
According to the engine, white is now up by 103 centipawns. |
| [Qc3] |
The engine best move was Qc3. |
| [Qc3 -> EGTB black win] |
The EGTB best move was Qc3 and would have led to a win for black. |
| bad move |
A textual representation for ??. |
TABLE 5.8: Annotation parts
23. Rg3 128/12#
| Part |
Description |
| 128 |
The engine could search up to depth 128. |
| 12# |
The engine has determined that white has a forced mate: black can be checkmated in 12 moves. |
TABLE 5.9: Annotation parts
29. g7 50/-3#
| Part |
Description |
| 50 |
The engine could search up to depth 50. |
| -3# |
The engine has determined that black has a forced mate: white can be checkmated in 3 moves. |
TABLE 5.10: Annotation parts
Only the main line is annotated. Variations are currently ignored.
The engine settings dialog allows you to configure chess engine settings.
The engine settings dialog can be accessed from:
Note that some of these settings may be absent if the engine does not support them.
| Item |
Description |
| Name |
Modify the name provided by the engine. |
| Cores |
Use a specific number of CPU cores. |
| Think on opponent's time |
Use pondering. |
| Opening book |
Select an opening book. |
| Principal variations |
The number of best moves to display. |
| Node limit |
If enabled, each game search is limited to the specified number of nodes (using the UCI go nodes command). This setting is ignored during analysis. |
TABLE 5.11: General settings
The options advertised by the engine are listed in this section.
If a text option is meant to accept a file, you can use the open button at the right of the text entry to select a file with the Android file selector. This is useful for using a custom neural network with engines such as Arasan, Stockfish or Lc0.
The opening book selection dialog allows you:
- add an opening book (press the ADD button);
- remove an opening book (long-press it then press Remove);
- select an opening book (press it).
The opening book selection dialog can be accessed from:
When a chess engine is configured to use an opening book:
- the engine is only queried if the opening book has no move for the searched position;
- during a game, the name of the opening book is appended to the engine name (for example Stockfish 12 + MyBook.bin).
The physical board settings dialog allows you to configure physical board and physical clock handling.
The physical board settings dialog can be accessed by pressing the settings button in the physical board page.
| Item |
Description |
| Stabletime delay |
Modify the stabletime delay. |
TABLE 5.13: Physical board settings
| Item |
Description |
| Sounds |
Toggle physical clock sounds. |
| Display last move |
Display the opponent move on the physical clock. |
| Display moves in capitals |
Display moves in capital letters. On a DGT3000, this is usually more readable than the standard notation. |
TABLE 5.14: Physical clock settings
The OTP settings dialog allows you to configure OTP mode.
The OTP settings dialog can be accessed by pressing the settings button in the OTP mode screen.
| Item |
Description |
| Display player info |
Display player information in each clock. Disabling this option might make more space available for the chessboards, which might be useful on a small screen. |
| Require clock taps |
Require players to tap their clock after each move. Enabling this option enables external clock mode. |
TABLE 5.15: OTP settings
Notable Acid Ape Chess features are detailed in this chapter.
Game data is implicitly shared between certain pages and dialogs.
The following sections describe the mechanisms involved in this process.
A game data source is a page which exports one or more game data items for use by a game data sink.
A game data sink is a page or dialog which imports one or more game data items from the active game data source (i.e. from the currently displayed page).
Game data items are:
- the displayed position;
- the game tree and properties;
- the state of the board flipped toggle.
The following pages are game data sources:
The following pages or dialogs are game data sinks:
To open the currently displayed position of a game page in a new position editor page, simply use Position > Edit in the main menu.
This uses the currently displayed game page (the active game data source) to initialize a newly created position editor page (the game data sink) with the currently displayed position and the board flipped state.
To analyze the currently edited position of a position editor page in a new game page, simply use Position > Analyze in the main menu.
This uses the currently displayed position editor page (the game data source) to initialize a newly created scratch game page (the game data sink) with the currently edited position and the board flipped state, then start analysis in that game page.
To analyze the current position of a physical board page in a new game page, simply use Position > Analyze in the main menu.
This uses the currently displayed physical board page (the game data source) to initialize a newly created scratch game page (the game data sink) with the current physical board position, then start analysis in that game page.
Acid Ape Chess provides a wide range of predefined time controls. You can also add custom time controls supporting multiple periods, move limits and Fischer increments.
| Name |
Spec |
Description |
| Custom |
N/A |
Use a custom time and Fischer increment selector. |
| Blitz |
3+2 |
Often used in FIDE-sanctioned blitz tournaments. |
| Rapid |
15+10 |
Often used in FIDE-sanctioned rapid tournaments. |
| Classical |
40/90+30 G/30+30 |
Often used in FIDE-sanctioned classical tournaments. |
| Classical Online |
120+30 |
Because online chess servers do not support advanced time controls. |
| World Championship |
40/100+30 20/50+30 G/15+30 |
Used in the classical games of the World Chess Championship 2021. |
| World Championship Rapid Tie Break |
25+10 |
Used in the rapid tie breaks of the World Chess Championship 2021. |
| World Championship Blitz Tie Break |
5+3 |
Used in the blitz tie breaks of the World Chess Championship 2021. |
| Armageddon White |
60/5 G/0+3 |
Often used by white in Armageddon tie breaks. |
| Armageddon Black |
60/4 G/0+3 |
Often used by black in Armageddon tie breaks. |
TABLE 6.3: Predefined time controls
In order to adhere to FIDE/USCF rules and to be consistent with the DGT3000, if a period specifies an increment, that increment is added to the initial time of the period (except for online games, because chess servers do not use these rules).
Examples:
- A 3+2 online game starts with clocks at 3.00;
- A 3+2 OTB/OTP game starts with clocks at 3.02;
- A 40/90+30 G/30+15 OTB/OTP game starts with clocks at 1:30.30. When a player enters the second period, 30 minutes and 15 seconds are added to his clock.
Pressing a draw button offers a draw to the opponent unless:
- the current position is a claimable draw (threefold repetition or fifty-move rule): the draw is claimed;
- your next move can potentially cause a claimable draw (threefold repetition or fifty-move rule): the claim draw on next user move feature is armed and the button icon changes to reflect this (a draw will atomically be claimed after you play the next move, if that move yields a claimable draw).
The arm feature is in accordance with the following rules of the FIDE Laws of Chess:
- « 9.2.1 The game is drawn, upon a correct claim by a player having the move, when the same position for at least the third time (not necessarily by a repetition of moves): »
- « 9.2.1.1 is about to appear, if he first writes his move, which cannot be changed, on his scoresheet and declares to the arbiter his intention to make this move, or »
- « 9.3 The game is drawn, upon a correct claim by a player having the move, if: »
- « 9.3.1 he writes his move, which cannot be changed, on his scoresheet and declares to the arbiter his intention to make this move which will result in the last 50 moves by each player having been made without the movement of any pawn and without any capture, or »
Acid Ape Chess provides instant access to Syzygy 7-men endgame tablebases.
When analysis is enabled and there are 7 or fewer pieces left on the board, Acid Ape Chess queries the Syzygy 7-men online service and displays the EGTB result as an extra move arrow.
Endgames tablebases can also be used to auto annotate compatible positions.
Chess960, also called Fischer Random Chess, is a chess variant that randomizes home ranks pieces.
Acid Ape Chess supports blindfold play:
- the board and move list are hidden;
- you input your own moves via speech recognition;
- opponent moves are announced via speech synthesis.
Acid Ape Chess uses move speech recognition in blindfold mode and when the recognize move button of the move list subpage is used.
Our move speech recognition algorithm was trained with US English speakers, so the recognition success rate may vary with your accent and pronunciation.
We are working on improving this algorithm.
Acid Ape Chess has extensive first-class support for FICS, ICC and Lichess.
This allows you to:
Acid Ape Chess supports UCI and CECP chess engines, and ships with these built-in engines:
- Arasan (UCI, by Jon Dart)
- cheng4 (UCI, by Martin Sedlak)
- Scorpio (CECP, by Daniel Shawul)
With a chess engine, you can:
Acid Ape Chess is compatible with apps that export chess engines via the following protocols:
- Open Exchange: a de facto standard on Android, used by numerous third-party engine apps;
- ACEI (Ape Chess Engine Interface): used by Chess Engines Collection.
When a compatible app is installed, Acid Ape Chess automatically detects and registers its chess engines.
You can add engine apps or binaries using the add toolbar button in the ENGINE or SIMUL tab of the New Game page, or in the engine manager page. The resulting dialog proposes a few popular chess engine apps and also allows you to add a custom engine binary.
Because of Google Play restrictions which took effect in November 2020, user-supplied and Open Exchange 1.0 chess engines are no longer supported on Android 10 and later.
To be compatible with Acid Ape Chess on Android 10 and later, a third-party engine must now be published as an Android app and use ACEI (Ape Chess Engine Interface) or Open Exchange 2.0.
Some commercial engines require manual license activation after installation. If this is the case and activation has not been performed, Acid Ape Chess cannot register the engine.
Activation is usually performed by launching the separate engine app once. Consult your engine documentation for details.
It is sometimes useful to have multiple copies of the same engine, each with different settings. For instance, you might want to have an engine duel itself with each side using a different opening book.
To clone an engine, access its context menu by long-pressing the engine in the ENGINE or SIMUL tab of the New Game page and choose Clone.
To remove a clone, access its context menu and choose Remove.
Acid Ape Chess reserves one CPU core for other tasks (the system, the Acid Ape Chess UI, other apps) and evenly shares the remaining cores amongst the engines running in a game page.
For instance, if your phone has 8 cores:
- analyzing with one engine (or playing against an engine) will allocate 7 cores to the engine;
- analyzing with two engines (or creating an engine duel) will allocate 3 cores to each engine.
This core allocation algorithm is per-task, not app-global (a task is a game or an analysis). This means that if you run multiple chess engine tasks simultaneously, you might exceed your device processor and/or memory capabilities (if your device becomes overloaded, it might freeze for long periods while trying to recover).
You can force an engine to use a specific number of cores via the engine settings dialog. Note that this only has effect for human vs engine games. Analysis, simuls and engine duels ignore this setting.
A chess engine uses your system to its full capacity and therefore drains your battery fast.
Chess engines continue to run while Acid Ape Chess is in the background, so that you can use other apps while analysis is running or while a chess engine is thinking during a game.
If chess engines are running while Acid Ape Chess is in the background, a system notification appears to remind you about battery usage. Pressing the Close button of the notification terminates the engines.
Acid Ape Chess allows you to play against multiple chess engines simultaneously.
This mimics real life simultaneous exhibitions and is an interesting way to play some chess.
To create a simul, use the New Game page's SIMUL tab.
In a simul:
- you play with White;
- you have unlimited time;
- each opponent is forced to play his move shortly after you arrive at his board.
The Acid Ape Chess online game database is maintained by Acid Ape Studios and provides:
- 210 million positions;
- 3.6 million games from the 1800s to 2023;
- 270,000 OTB players from club players to superstars.
This database is updated continuously.
The online game database is used by:
Acid Ape Chess allows you to play on a connected physical chessboard.
A physical clock can optionally be connected to that board.
TABLE 6.4: Supported physical boards
To connect to a USB board, simply plug the board into your phone or tablet. You can also use the physical board page to test your board once it is connected.
Make sure that the
OTG side of your cabling is plugged into your phone or tablet.
When a physical board is connected, specific squares may be highlighted on the Acid Ape Chess virtual board.
Acid Ape Chess automatically detects the orientation of the physical board. That is, you can place the black pieces on the white side. This is especially useful for boards which do not have coordinates.
The stabletime feature causes Acid Ape Chess to wait for the board to stabilize before considering a change.
It is used to avoid misdetection of sliding in double-step pawn advances and bishop/rook/queen moves.
The wait delay defaults to 400 ms and can be modified from the physical board settings dialog.
The algorithm is smart enough and inhibits itself when a move can not be further extended.
For instance, when playing 1. e3, the stabletime delay is in effect because the move can further be extended to 1. e4. However, when the e4 square is reached, the move is applied immediately because it can not be further extended.
The result of a game can be encoded by placing the kings on two of the center squares (d4, d5, e4 and e5).
To use this encoding feature, make sure that the first king move is an illegal move. If it is not, first remove both kings before placing them back in the center squares.
To encode a white win, place both kings on light squares: d5 and e4.
To encode a black win, place both kings on dark squares: d4 and e5.
To encode a draw, place both kings on squares of opposite colors: d4 and e4, d5 and e5, d5 and d4, or e5 and e4.
When a chess clock is connected to a supported physical board, Acid Ape Chess can use it for display or as time source.
Moreover, a physical clock is a tap input source for external clock mode.
Acid Ape Chess supports the DGT3000 connected to any DGT board model.
- Connect the DGT3000 to your chessboard.
- Connect Acid Ape Chess to your chessboard.
- Use the physical board page to verify that the DGT3000 is recognized by Acid Ape Chess.
Acid Ape Chess supports the DGT Pi, as the DGT Pi can be used as a regular DGT3000 clock. For more details, consult the DGT Pi manual.
In this mode, Acid Ape Chess is the time source: it displays its own data on the physical clock, controls the clock beeps and detects when a button is pressed on the clock.
To use this mode, select option 25 on the physical clock.
When option 25 is in use, the DGT3000 is quite laggy. This may adversely impact the players experience, particularly in blitz games. For two-player games, it is recommended that you use an option other than 25.
In this mode, the physical clock is the time source: Acid Ape Chess displays the physical clock data on its own virtual clocks. Acid Ape Chess is not responsible for timekeeping: it merely listens to time updates sent by the physical clock.
To use this mode:
- open the play dialog;
- select two human players;
- select an option other than 25 on your physical clock.
This mode is only available for local two-player games. For other game types, use option 25.
This mode reduces clock lag but does not entirely eliminate it: it is still substantial when using a DGT e-Board. However, one of the advantages of using this mode is that the physical clock is autonomous: players will not experience any lag when looking at the physical clock after having tapped it.
When playing OTB games with a physical board but no physical clock, the fullscreen clock can be used as a virtual clock that players must tap to confirm their move (the fullscreen clock is a tap input source for external clock mode).
The fullscreen clock can be enabled by pressing the FULLSCREEN CLOCK button of the game information subpage (on smaller screens, you might have to scroll the subpage down a bit to reach that button).
This button only appear when relevant (you don't want a fullscreen clock if you have to input the moves with the virtual board).
When a physical clock is connected, the top center status icon appears.
| Icon |
Description |
 |
A physical clock is connected, and its lever is up on the left side. |
 |
A physical clock is connected, and its lever is up on the right side. |
TABLE 6.7: Top center status icons
When a physical board is connected, the bottom center status icon appears.
Side-specific status icons may appear in the lower left or lower right corner of the clock.
Additionally, if a side's time control has multiple periods, the current period number for that side is indicated near the bottom center part of the screen.
OTP stands for over the phone. With OTP mode, two players can play against each other on the same phone or tablet. OTP mode can also be a useful visualization when two players are playing on a physical board.
If the Require clock taps option is enabled in the OTP settings dialog, OTP mode is a tap input source for external clock mode:
- before white can move, the arbiter must start the clock (by pressing the play button in the central toolbar);
- players must tap their clock to confirm their move.
To enable OTP mode:
- Create a two-player game by using Position > Play in the main menu.
- Press the OTP MODE button of the game information subpage (on smaller screens, you might have to scroll the subpage down a bit to reach that button).
When a physical clock is connected, the top center status icon appears.
| Icon |
Description |
 |
A physical clock is connected, and its lever is up on the left side. |
 |
A physical clock is connected, and its lever is up on the right side. |
TABLE 6.10: Top center status icons
When a physical board is connected, the bottom center status icon appears.
Side-specific status icons may appear at the left or at the right of the side's clock.
Additionally, if a side's time control has multiple periods, the current period number for that side is indicated in the side's clock.
External clock mode requires the use of a physical or virtual chess clock to:
- start the game clock (by pressing the play/pause button);
- confirm a move (by tapping the relevant clock side).
A move arrow indicates a legal move that has been played on the chessboard but not yet confirmed by a clock tap.
When a physical chessboard is connected and the game is a human duel, external clock mode is active if any of the following conditions are true:
When OTP mode is enabled, external clock mode is active if the Require clock taps option is enabled in the OTP settings dialog.
Acid Ape Chess automatically saves played, adjourned and observed games.
Your saved games can be reached with the PGN explorer page.
Games of different types are saved in different locations.
In the following table the listed files are relative to Acid Ape Chess/Games, which is the Home location of the PGN explorer page.
TABLE 6.12: Game autosave locations
You can adjourn engine games and human duels, and resume playing at a later time.
Your adjourned games are autosaved to My adjourned games.pgn and can be reached with the PGN explorer page.
To adjourn a game in progress, quit the game by pressing the Back button. If the game type supports adjournment, the quit dialog will feature an ADJOURN button in addition to the RESIGN button.
Press the ADJOURN button to mark the game as adjourned and save it to My adjourned games.pgn. The game page will then be closed.
To resume an adjourned game, reach the adjourned game with the PGN explorer page, then press the game.
Finished games are automatically removed from My adjourned games.pgn.
Since Acid Ape Chess saves adjournment metadata in custom PGN tags inside the game, you can share it with a friend (or with another of your devices) using the game sharing feature.
If the game recipient is also using Acid Ape Chess, opening the PGN file will automatically resume the game.
Acid Ape Chess allows you to share your games as downloadable PGN files.
To share the current game, use Game > Share in the main menu.
When you share a game, Acid Ape Chess uploads the PGN file to its backend server, which replies with a unique download link for the PGN file.
This download link is then shared with the standard Android share mechanism.
