3D chess

Three-dimensional chess or 3D chess is any of various chess variants played on three-dimensional boards. Three-dimensional variants have existed since the late 19th century. One of the oldest versions is Raumschach (German for "Space chess"), invented in 1907 by Ferdinand Maack and played on a 5×5×5 board. Maack founded a Raumschach club in Hamburg in 1919, which remained active until the Second World War. "Three-dimensional chess" is also often used figuratively, to describe any very difficult endeavor (as, for example, "[Nancy Pelosi] is a master of the three-dimensional chess of House politics").