There are 1000s of variations of chess. Triangular chess and Quatrochess allow 3 and 4 player games. Infinite chess has an unbounded board whereas Alice chess plays with two boards. Dunsany’s chess is a regular chess army versus a large army of pawns. Kriegspiel is when you can’t see the opponents pieces. Almost chess uses chancellor pieces instead of queens. Losing chess changes the objective to losing all of your pieces.

Bobby Fischer created a variation of shuffle chess called Chess960 where the back row is randomized while following certain rules like bishops have to be on opposite colors and the king has to be between the rooks. He wanted to favor creativity over memorization.

Einstein chess is based on his theory of relativity. When a piece is moved it loses energy and is demoted. When a piece captures another it gains energy and is promoted.