Remove all of your opponent's pieces of the same species to win.
The object in Extinction Chess is to win by capturing pieces of the same type making that “species” extinct.
As the aim of the game is not checkmate, the King holds no special status in this variant and can be captured. There can even be multiple on the board at once!
This variant is played from the standard starting position of Standard Chess.
The moves of the pieces remains the same as Standard Chess.
Pawns can promoted to any piece (other than a pawn!) including a King.
Promoted Pawns are no longer considered Pawns. Promoting every pawn would result in their extinction losing the game.
Castling rules remain the same, but the King can castle through check or when in check.
En passant rules remains the same as Standard Chess.
The King has no special value and can even be captured.
Extinction chess is won by capturing all pieces of a single type from the board. This includes any promoted pieces of a type too.
Therefore, you win by capturing any of the following - all of your opponent's Kings, Queens, Rook, Bishops, Knights or Pawns. If your opponent promotes their last pawn, you win too.