The game is almost like normal chess. However, it is played on a 7x8 board instead of 8x8. This leads to many more situations with "en passant" moves. See for instance the opening line: 1. d2-d4 c6-c4 2. d4xc5 ep
 
Two series of test games of Zillions (in "high variability" mode) versus itself were played:

• The first series with eight games was normal chess on the traditional 8x8 board. In all these games only one(!) "en passant" move happened.
• The second series also had eight games, but was played on the 7x8 board. In this series altogether nine(!) "en passant" moves were played.