Knightmare Chess is a fantasy chess variant published by Steve Jackson Games in 1996. It is a translation of a French game Tempête sur l'échiquier ("Storm on the Chessboard"), designed by Pierre Cléquin and Bruno Faidutti.
Knightmare Chess is played with cards that change the default rules of chess. The cards might change how a piece moves, move opponent's pieces, create special squares on the board or do something even wilder. For example, a card called Demotion says:

Knightmare Chess - Chess played with cards. Each card breaks the rules in a wild and unpredictable way, giving the game more twists and turns than a roller coaster.
Knightmare Chess Resource Page - Tips, strategy and information on Knightmare Chess, the chess/collectible card game from Steve Jackson Games.
| Let's Play The Haunted Mansion - Part 18 - Museum ~Damn Those Knights!! | |