Raumschach

Raumschach (German for "Space chess") was developed in the early 1900s by German mathematician Ferdinand Maack (1861–1930). He may have been influenced by an earlier 3D chess game designed by Lionel Kieseritzky, called Kubikschach (Cubic Chess). Maack's original design was for an 8x8x8 board, but after extensive testing, he realized this was too large to be a playable game. Maack therefore promoted two main variants of Space chess in his later publications on the game, a "four level game" (on a 4x4x4 board) which used the standard chess pieces and a "five level game" (5x5x5) which added the unicorn piece (which moves triagonally, i.e. through the corners of a cubic cell).

The main sources for these games are Maack's Spielregeln zum Raumschach (Rules of Space Chess, 1913) and Raumschach: Einführung in die Spielpraxis (Space chess: Introduction to the Practice of the Game, 1919). In the second post-war publication, Maack also mentions a seven level game (7x7x7) with another new piece, the giraffe (or "two horn"), but this does not seem to have been widely played or discussed. Raumschach was played in the Hamburg Raumschach Club (possibly founded in 1909), which remained active until WW2. Members included chess problemists like Hans Klüver and Willibald Roese. Raumschach was also discussed by the English problemist Thomas Rayner Dawson (1889–1951), who published several Space chess problems and articles on the game, and designed his own three-dimensional chess variants and 3d fairy pieces.