Chellt
From Jenny Everywhere Wiki
Chellt was a variant of the game of chess which came from the planet Tetrayon-Nine. According to Century Smith, who once tried to explain the rules of the game to Briar to cheer her up, it involved “the fourth dimension and the spontaneous creation of a localized miniature time loop”. Because of this, playing chellt required fairly specific, advanced equipment. (PROSE: Century Smith and the Time Terror)