Chess Mega Bundle

Chess finally has its own 200-in-1 multicart. Atomic, 960, double 960, Horde, three-player and four-player chess - if you can name a chess variant, it's probably in here.
The design is functional but very bare - you can pick different board and piece designs, but it's missing a couple of niceties present in other chess clients. In particular, there's no move list or analysis board, which is disappointing (if understandable -- I don't envy the person who has to figure out algebraic notation for a circular board). The sound effects are also missing alerts for captures or checks.
You will want a friend to play with: I haven't found any open games online at the time of writing. While there is an AI which mostly adapts well to the different variants, the real fun is in playing against people who make horrible mistakes because they forgot pawns move sideways now, and take advantage of your mistakes in turn (because you also forgot pawns move sideways)
It won't be your main chess client, but for the price Chess Mega Bundle is a great diversion after an extended bout of blitz/rapid chess.