In Valiant Chess (also V-chess) the knight pawn, having advanced to the fifth rank, can jump like a knight to an empty square, east-north-east or west-north-west. Only knight pawns on the fifth rank have this capability. The pawn loses this capability when it advances to the 6th rank. Compared with standard chess, this means that an advanced knight pawn is endowed with an extra jump move. Valiant Chess is specially designed for rapidchess, since it makes the game more aggressive and less monotonous. Aggressive play on the flanks is facilitated as the Valiant pawn makes it possible to pry open the pawn chain, something which greatly enhances attacking play. In this way one can open the file in order to attack the king, or disrupt the position for attacking purposes. This new rule favours the advance of the knight pawn, which leads to a more aggressive game.
More information, a Zillions program, and a preset for online play, is here:http://hem.passagen.se/melki9/valiantchess.htm