In Pioneer 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.

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. (Should both players exclude the external piece(s), then they must be removed by clicking on them.) 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 must now be placed on the file on which the player intends to introduce the piece(s). If, for instance, the player places the external piece behind his own queen, then the piece is automatically introduced on the queen's initial square when the queen moves away. If a piece is placed behind the king then it is also introduced at castling. The same is true if the external piece is placed behind the rook. Should a piece on the initial position be captured (exchanged), then the player has forfeited his right to introduce an external piece placed behind it. Note! In variants with two external pieces per player, the player is not allowed to position one piece on the king file and one on the rook file. This rule will prevent him from introducing two pieces simultaneously at castling.