Invented by R. Wayne Schmittberger and added here with his permission. You win by eliminating any one type of your opponent's pieces. Both bishops, for example.
1. Game rules
The game starts from the standard chess setup, and all the pieces move as in standard chess.
The game ends once one of the players eliminates any type of the opponent's pieces. Thus, a player who loses either his King, his Queen, his two Rooks, his two Bishops, his two Knights, or his eight Pawns, loses the game (barring a promotion).
Check and checkmate do not apply. Pawns may promote to any other type of piece, including Kings. When a Pawn promotes to some type of piece, this piece is also counted among the pieces of the type; e.g., when a Pawn promotes to a Queen, and the other Queen is captured, then the Queens are not considered to be extinct, i.e., the game continues. If a player promotes his last Pawn, he loses (as his Pawns are now extinct), unless he wins by extinction on that very move.
Since there is no check, castling under or through check is allowed.
2. Hints, tips, tricks
If you take your opponent's last piece of one kind, you immediately win, even if your piece could be recaptured on the very next move. So, what would be a usual queen exchange in standard chess, is a win here.
It is worth repeating: there is no check. If you attack the opponent's king, but he can capture your queen (or your last knight, or...), he will do that and win the game.
Especially in closed positions, it can be a good idea to sacrifice a rook for a minor piece if the opportunity arises. The opponent's remaining minor piece can then be hunted, while your second rook is not too likely to be troubled.
As there is no check, many tactical patterns from standard chess do not apply here. Beware! For example, in this game White expected to win the queen, but lost his own instead. Also, there is no absolute pin here.
More suggestions welcome
3. Example games
Commented Game published in the journal
Example game where both players have several pawns, but only ONE piece of each type (King, Queen, Rook, Bishop, and Knight). A different strategy must be used, since capture of any piece (except for pawns) ends the game.
Dense tactical struggle - notice many non-chess-like moves (like lack of recapture or piece being given up) related to different threats both players make
Straight for the bishop - after black gives up one of his bishops, white goes straight for the other one (note: if 10... Bxb7 then 11.Ba6)
More welcome