Battle chess revisited
Not exactly an original concept, but really neatly executed. I remember spending many an hour trying to see all of the animations in the original battle chess, so having the execution menu is an excellent addition.
And any chess game that lets you play en passant is very thoroughly researched and well made in my opinion.
My only gripe is that the computer isn't the smartest though getting it to play even semi-intelligently is impressive- I've seen much much worse. It's real issue is that it will sacrifice pieces relentlessly to stop you from taking the queen (or other high value piece), when it would be better off just letting you have it in the first place and making the best of a bad situation (in one case it gave me a rook, bishop and knight before finally relinquishing the queen).
Oh, and can we have knights, not horses in future please...