In Accessory Chess the rules are the same as in orthodox chess, except that one extra piece (or two) per player is placed in the reserve. Standard chess is included as an option, thereby maintaining the historical connection. In a tournament, by way of the initial voting procedure, players can decide to play a traditional game.

Before starting, the players must decide whether they want to use the extra piece. To make a decision, press on the little black square. Only if both players choose not to use the extra piece, then it becomes a regular game of chess. If white turns down the extra piece, then black can overrule this. Each variant features a particular extra piece. Choose your own favourite. Right-click on a piece to get more information.

If players have elected to include external pieces, they may either move a piece or pawn, or drop the extra piece from the reserve. Pieces may only be dropped on a friendly pawn on the second rank. The removed friendly pawn must immediately be relocated one square ahead of the dropped piece. This position must be empty. If not, the piece cannot be dropped on the friendly pawn. Should a player refrain from inserting his extra piece at these occasions, then he has forfeited his chance of introducing it. Note that pieces and pawns are allowed to move before the extra piece has been dropped. You are allowed to make a pawn-relocation if in check, if the pawn-relocation covers the check.

It's a difficult strategical question whether one should wait, or immediately make use of the drop move to advance a pawn. But dropping the extra piece on the king- or queen pawn could block the development of the bishop. Waiting has its obvious advantages, although the alternative positions where the piece can be dropped will become fewer and fewer.

Accessory Chess is intended as an alternative to standard chess. This implementation will allow the user to test which pieces are suitable. It will be enhanced with more alternative pieces in later editions. Accessory Chess is closely related to Alternative Chess, Pioneer Chess and Pilgrim Chess.

You can play Accessory Chess (with Divaricator) online and by e-mail here.