Four-dimensional chess

Four-dimensional chess, or 4-D chess, was a Time Lord variant of the Earthly game of chess which was "very popular" on Gallifrey. (GAME: )

Rollo was a skilled 4-D chess player. (GAME: )

The Entity considered four dimensional chess to be an "elegantly simple" game. (PROSE: )

Nature
The game shared the basic rules of Earth chess, (GAME: ) including the use of chess pieces such as Kings, (PROSE: ) but could be played on "multiple levels" (GAME: ) or on an ever-increasingly fast translucent sphere whose board pattern changed over the course of the game, which resulted in the "structure of the conflict" being rearranged every time. (PROSE: ) The pieces were capable of time travel, (GAME:, PROSE: ) being able to dematerialise from the board and materialise elsewhere on later turns of the games, (GAME: ) as well as moves occurring the future being twist back on themselves to affect moves made in the present. The pieces also increased in number over the course of a game. (PROSE: )

Known challenges
The Mandarin and the Entity once played a match in the non-world where the Entity was banished. The game was played until the Mandarin began to lose, so he strategically manoeuvred the game to result in a stalemate. (PROSE: )