Chad (chess variant)

Chad is a chess variant for two players created by Christian Freeling in 1979. It is played on an uncheckered 12×12 gameboard with one king and eight rooks per side, where rooks are able to promote to queens.
The inventor's aim was "to create a game of tactical and strategical depth that was both simple and elegant to express the concept of "mate"—the 'pure' chess game". The game was played for many years at the Fanaat games club in the Netherlands and was featured in the periodical "The Gamer" 6 in May–June 1982.
Game rules.
Each player owns a "castle" consisting of 3×3 squares surrounded by a "wall" of 12 squares. A king may not leave its 3×3 castle, but the rooks are free to move unimpeded by castles or walls.
As in chess, White moves first, a capturing piece replaces the piece captured, and checkmate wins the game.
References.
Bibliography