All of the math Olympians were experts in generating ideas that might prove useful. Even when they were not doing math, they often seemed to be exercising their creative faculties. At the training camp, for example, they rarely played regular chess, which they considered too boring, but they incessantly played chess variants. In the game known as suicide chess, the object is to be the first player to lose all your pieces. In atomic chess, whenever a piece is captured, so are all the pieces on adjacent squares. The board in toroidal chess is connected from side to side and from front to back, so a piece can move off one side of the board and reappear on the other side. In proxy chess each piece has the moves of the piece to its immediate left. And the Olympians were especially fond of bughouse, a devilishly complex game played against the clock with two chessboards, in which captured pieces immediately reenter the game on the other board.
Exerpt from Count Down: The Race for Beautiful Solutions at the International Mathematical Olympiad by Steve Olson