Maximus version 1.11, 1.12, 2.0

October 2017 © 2008-2021 J.J. van Horssen


Under Construction


Maximus is a program for the game of draughts (or checkers) on the 10x10 board, according to the international rules (see





  1. The Function of the Buttons in the Main Screen
  2. Entering and Taking Back a Move (and Hint)
  3. Playing a Game with White or Black
  4. Entering Multiple Moves or a Complete Game
  5. The Menu
  6. How to E-mail, Save, Open, Delete and Import a Game
  7. (Automatically) Analyzing a Game; the Graph



1. The Function of the Buttons in the Main Screen


From left to right:

*      : go back one move (the clock stops)

*      : go forward one move (the clock stops)

*      : the think button; start thinking about a move (the players switch colors)

*      : the stop button; stop thinking (and play the best move), stop pondering, stop clock, etc.

*      : the input button: input mode on/off (see below)

*      : the menu button; open the menu (or exit setup position)


As long as Maximus is thinking about a move, it is not possible to go back or forward one move, or to open the menu. You can use the stop button to interrupt the search.


Tap the info icon () or the search information next to that (‘Depth X Value Y  ZZ-ZZ …’) to show the graph with search or analysis values. The graph can be shown at any time during a game, except when you are playing against one of the training levels. See the Graph.



2. Entering and Taking Back a Move (and Hint)


Enter your move by dragging a piece to an empty square and dropping it there, or alternatively by tapping squares. In the latter case you first have to tap the piece you want to move, and then the square you want it to move to. The selected squares are marked with a green edge. In case of a multiple capture, you sometimes have to choose between different ways of capturing. In that case, also tap one or more of the intermediate squares. As soon as Maximus has sufficient information to uniquely identify a move, the move will be played on the board. This also applies if you tap an empty square to which only one piece can move. If you tap a piece or square that does not belong to a legal move, Maximus will mark all pieces that can move with a red edge, or in case of a forced move the relevant move.

You can take back moves by you and Maximus by tapping the left arrow button when it is your turn to move. After that, you can use the right arrow button to go forward again until the last position in the game, or you can play a new move or ask Maximus to do so any time you like.

You can also use the think button if you would like a hint for the move you are about to play. You can always take back this move and play another one.



3. Playing a Game with White or Black


If you want to play a game with White, just make your first move. Maximus will respond with a countermove. The played moves are shown on the board, where the relevant squares are marked with a green edge. As long as Maximus is thinking, a green light is visible at the top right of the screen, next to the clock.

To play a game with Black, tap the menu button at the bottom right. In the menu, choose Turn Board. If necessary, also choose New Game. You return to the main screen. Now tap the think button. The player names of White and Black are switched and Maximus starts thinking about its first move.



4. Entering Multiple Moves or a Complete Game


If you want to enter multiple moves in a row, for instance an opening you wish to play against Maximus, tap the input button. A small board appears in the magnifying glass, as a sign that input mode is now switched on. In this mode, Maximus does not respond to the moves that you enter with a countermove. You can also use this mode to enter a complete game (and e-mail it), as a travel draughts set or -if the screen size allows for this- to play against someone else.

By tapping the input button a second time you can again start playing against Maximus.



5. The Menu


Using the menu button you enter the main menu. This offers the following options:


New Game:

put the board in the initial position, erase the current game, reset the clock, and go back to the main screen.


Replay Game:

return to the main screen and start replaying the game automatically, from the current position to the end of the game. If you are at the end of the game, Maximus will automatically jump to the first position of the game. You can stop the replaying by tapping the stop button.



show the Notation screen. In this screen you can see the game data and the played moves. you can edit the data, except for FEN (a setup position). You can scroll through the moves in case these do not fit on the screen. By tapping a certain move you return to the main screen at the selected position in the game.

You can e-mail your game (in PDN format) by tapping the E-mail button. It is also possible to save games and later to reopen them. For this, tap the Storage button (see below).


Turn Board:

turn the board (again) and return to the main screen. You can always see whether the board is turned by the square number 1 that is displayed at the bottom right square if the board is turned.


Setup Position:

return to the main screen in ‘Setup Position’ mode. All buttons except the menu button disappear. You can clear the board by just swiping your finger over the board. Next you can place pieces by tapping empty squares, starting with the white men. If you want to change the type of piece that has to be placed, tap multiple times on the same square until the desired piece (or an empty square) appears.

To change the color-to-move, tap the white corner square on the side of the board of the player that is to move. For White this is the corner square next to square 50, for Black the corner square next to square 1. The color-to-move is shown by a white checkmark after the name of the player that is to move. Next to the checkmark the move number is shown during the game.

To finish setup mode, tap the menu button again. The other buttons reappear and you can start playing. If you changed the position, the current game will be erased. If you return from setup mode without making any changes, the current game is preserved.


Maximus vs Maximus:

let Maximus play against itself, from the current position with the current playing tempo. You can stop the automatic game by tapping the stop button.



show the Level screen. Choose 1 mode out of 4 options:

-         Training Level: from level 0 (rules; Maximus plays a random move) up to and including level VII

-         Seconds Per Move: 1 second per move usually plays a stronger game than Level VII

-         Time Schedule: for instance first 50 moves in 10 minutes, then 25 in 5 minutes, and finally 5 extra Fischer seconds until the end of the game. Maximus will now try to better distribute the time it uses for each move, compared to a fixed amount of time per move.

-         Fischer: according to the Fischer-system, starting with a limited amount of time (minutes) and a number of bonus seconds for each move played.

Maximus has an opening book for the first moves of the game, which is not used for the training levels.



show the Clock screen, where you can set the clock for White and Black. Normally you will not need this. Starting a new game or choosing a new playing level mode will automatically reset the clock, depending on the selected playing level mode. But if you want you can change the clock settings here.



show the Settings screen. Here you can change the following settings:

-         Your Name: enter your name.

-         Language: change the selected language.

-         Processors: set the number of processors (or threads) that Maximus is allowed to use. Check the number of processor cores of your device. Do not set the number of processors to a number greater than your device supports. The more processors Maximus can use, the stronger it will play.

-         Transposition Table: the size of the position memory. The bigger the table, the stronger Maximus will play. Usually 16 MB is sufficient. This also depends on the available memory of your smartphone or tablet. Experiment with this if you like. If you get a memory error message you have to use a smaller amount of memory. If necessary, restart or reinstall the program.

-         Pondering: thinking in the opponent’s time. If this option is selected, Maximus will also think when it is your turn. A yellow light on the top right of the screen indicates this. Of course this also increases the playing strength of Maximus.

-         Show Engine Info and PV: during the search, show the search depth, search value and principal variation. This information is not shown when playing against the training levels.

-         Show Square Numbers: show the standard square numbers 1 to 50.


Automatic Analysis:

See (Automatically) Analyzing a Game.



show this help.



6. How to E-mail, Save, Open, Delete and Import a Game


Choose Menu, Notation… to open the Notation screen. Here you can e-mail your game by tapping the E-mail button, which will open the mail application on your device. Or tap the Storage… button to open the Storage screen. Here you can manage your games. Choose Save to save the current game. Enter a name for the game in the dialog and choose OK. Maximus will ask for your confirmation if there is already a game by this name.

To open a game, first select it in the list and then tap Open. You return to the Notation screen, where the game data and moves are shown.

To delete a game, first select it in the list and then tap Delete. Maximus will ask your permission first before the game is actually deleted.

It is recommended that you e-mail to yourself the games you want to store permanently.

You can also import a game or position into Maximus by copying it to the clipboard, for instance from a web page or an e-mail, and pasting it into the text input area in the Import screen. You can open this by tapping the Import button in the Notation screen. You can enter a game in PDN format of a position in FEN format. Tap the Import button to import the game or position. If the game or position is recognized, you return to the Notation screen. If not, you will see an error message and you can edit the input. For a description of PDN and FEN refer to



7. (Automatically) Analyzing a Game; the Graph


If you want to analyze your game, for instance to see where mistakes were made, you can do this by selecting both Pondering and Show Engine Info and PV in the Settings screen. Via the Notation screen you can go to the start of the game, or to the point where you want to start analyzing. Maximus will start pondering on the current position, showing the search depth, search value and principal variation. Using the arrow buttons to browse back and forth in the game, you can see how the search value changes. Of course, the longer you let Maximus think, the more reliable are the search value and best move. As long as you do not enter moves or tap the think button, the game remains intact.

You can also (first) get your game analyzed automatically. In the menu, choose ‘Automatic Analysis’. Maximus will start analyzing the game backwards, from the current position till the start of the game, or until you tap the stop button. So you can easily have parts of a game analyzed, or re-analyze certain parts with more thinking time. The analysis function automatically switches to playing mode ‘Seconds Per Move’, and uses the number of seconds specified there to analyze each move. When the analysis is done, the analysis report is shown through the e-mail interface. In the analysis report, Maximus provides an alternative for each move that makes the search value change 0.1 point or more, and a diagram for each change of 0.5 point or more.

At the end of the analysis, also the analysis graph is shown. In the graph, the X-axis represents the game moves, whereas the Y-axis represents the values. A value of +1 means that white has an advantage worth one man. Values greater than +10 or less than -10 are truncated. The red vertical line shows the current position in the game. White squares represent values of positions with white to move, black squares represent values of positions with black to move. If you have your game analyzed, a value will be available for every position. However, if you play a game (e.g., against level 1 second per move) then only positions of Maximus’ color will be assigned a value.

If you store a game (after analyzing), the search (or analysis) values will be stored as well.



Enjoy Maximus!



Mail your questions, remarks and games (please state device and settings) to: