Antichess

Lose all your pieces (or get stalemated) to win the game.

Pieces move the same way they do in standard chess; however, kings lose
their royal powers - they cannot castle, and checks are no longer a threat.
Since kings have lost their royal powers, pawns may be promoted to kings.
Capturing is forced. If you can take a piece, you must. If multiple pieces can
be captured, you may choose which piece you capture.