Berolina

Berolina chess, also called Berlin chess, is a chess variant employing the Berolina pawn (Wikipedia). Berolina chess follows the same rules as standard chess, except that all the pawns are replaced by Berolina pawns.

The Berolina pawn moves, without capturing, one square diagonally forward. It captures one square straight forward. The Berolina has the option to move two squares diagonally forward on its first move. It can also capture en passant: a Berolina pawn, attacking a square that has just been bypassed by an enemy pawn's two-square advance, may capture the enemy pawn as if it had moved only one square. Like the orthodox pawn, the Berolina pawn is promoted when it reaches its last rank.