Chess Variants/Berolina Chess

Introduction
Berolina Chess is a variant named after its titular piece, the Berolina pawn (also known as the Berlin pawn or anti-pawn).

History
The Berolina pawn was invented by a German, Edmund Hebermann, and named after the German capital city Berlin. It can be assumed that Berolina chess was created at the same time.

Rules
Berolina chess is played just like the standard game, with one exception - all of the pawns are replaced with Berolina pawns.

When moving passively, the Berolina pawn moves one square diagonally forward. When it captures, it moves one square straight forward. (This is essentially the inverse of a standard pawn.)

On its first move, a Berolina pawn may move two squares diagonally forward. En passant is possible as well (see the diagram for details):

When a Berolina pawn reaches the furthest rank from where it starts, it promotes just like a typical pawn.

Sub-variants

 * Berolina Plus Chess uses Berolina Plus pawns, which move in the same manner as standard Berolina pawns, but may also capture one square sideways.