Play-test applet for chess variants

Introduction

This page contains a tool that can help you play testing your chess-variant designs, by playing those against the generic AI of the Interactive Diagram. You just have to set up the initial position by specifying a board format (and pressing 'Apply'), and moving the pieces you want to participate from the table to the board. (You can drag them one by one, but as long as you are still in setup mode you can make multiple clicks on empty squares to place a bunch of them, and the opponent will automatically be placed as mirror image.) When the setup is as you want it, you can press 'Start Position' to let the computer know you are done. You can then press the 'Play it!' link below the board to start playing your variant against the AI.

You should primarily select the pieces by the desired image; When you are not happy about the move, name or ID that comes with it you can all change these: Just specify what you would like to have instead for a certain piece, and then click the move of that piece in the table. This should immediately display all new values for that piece. If you want to use the same image for two different pieces, you can use the 'Duplicate' button after selecting the piece.

The replacement move has to be entered in Betza notation (the XBetza extensions are understood). For people not familiar with that notation there is an aid for creating it near the bottom of the page; It doesn't handle really complex cases, such as bent sliders or locusts; for those you would really have to type the move. But the chances that you need any of those (that are not already in the table) are quite slim.

Move definition aid

In the pane below you can define moves of a piece by clicking the squares it should be allowed to move to. First click defines a leaper move to the square. A second click would convert this to a slider/rider move that repeats that step/leap. A third click would remove the move again.

To limit the range of a slider you can click the first square along its path that it should not be able to reach. Clicking on the piece takes away all its moves, and thus clears the entire pane.

Once you are happy with the move diagram you created in the entry panel, press one of the buttons to the right of it to add the move to the Betza description text entry. (Don't forget to clear that first, by pressing 'Clear All'!) You have a choice to add it as move-only, capture-only or both.

Before you click one of these buttons you can specify a few other properties of the move through tick boxes: whether it is to be used as initial move (i.e. on pieces that have not moved before), whether it should hop over one other piece (only sensible with rider moves), or whether it should be non-jumping (not sensible with leaps to adjacent squares). You would only rarely need any of those, so by default the checkboxes are unticked.

Note that you can always edit the move description that you created this way before you actually assign it to a piece in the table. E.g. when you needed a range limitation on a slider too large to fit into the panel; you would just specify a smaller range, and change the number in the resulting definition by typing.

As an example: to specify a FIDE Pawn you would click the square before the piece (forward is up!) and enter it by pressing 'Move-only'. Then you would click the squares diagonally in front, tick 'Also as en-passant capture', and press 'Capture-only'. Finally you would click the square two steps in front of the piece, tick the 'Initial move' and 'Non-jumping' checkboxes, and again press 'Move-only'. That should have filled the Betza move-description text entry with the Betza notation for the move of the FIDE Pawn.

Last revised by H. G. Muller.