Stereo-Chess

Stereo-Chess is a three-dimensional chess variant, invented in 1975 by Gerhard W. Jensch in 1975. Jensch (1920-1990) was a German chess problem composer, and is known for his column in Schach-Echo and Presidentship of the FIDE Permanent Commission for Chess Composition.

Jensch wrote a book on this game, but as far as I know, the book is not published.

In the sixteenth issue of Variant Chess (winter 1995), Peter Wood writes about Stereo-Chess. He characterizes this game as reputed to be the most playable of the several 3D-chess variants. Problems have also be composed for this game.

Rules

The board

The board is formed by adding to a normal chess board (i.e., of eighth by eighth squares) four extra boards of four by four squares. These are stacked on top of the central 16 squares of the first chess board, i.e., above the squares in the area c3-f3-f6-c6.

The lower-left corners of the various boards are alternatively colored white and black: this corner of the 8 by 8 board is black (as usual); this corner of the 4 by 4 board directly above it is white; for the board above that it is black, then again white, and the lower-left corner of the upper 4 by 4 board is black.

The squares on the four 4x4 boards get a letter A, B, C, or D (A denoting the lowest, D the highest of these boards) plus the name of the square on the 8 by 8 board directly below it.

The game starts with the standard set of pieces arranged in the usual manner on the eight by eight board; the four smaller boards are empty in the opening setup.

Moves

Rooks move in straight lines, either on the board they are (as a normal rook move), or up or down.

A bishop moves diagonally on the board it occupies (i.e., a normal bishops move), or moves diagonally up: it either stays in the same row, or column, and goes as many squares up/down as it goes sidewides, forward, backward. So, one coordinate of the bishop stays the same, and two of them are changed.

The queen has the moves of the rook, the bishop, but can also go diagonally in all three directions, e.g., from b2 on the lower (8 by 8) board to Df6, the upper-right square on the top board.

The king moves as a queen, but only one step. Thus, a king on the middle of one of the middle boards can go to 26 squares.

A knight makes a knights move on a board, or one in `another plane'; for instance, a knight can go from Ac3 to a3, to Ad5, Bc5, Cd3, etc.

A pawn can move, without taking, one square forward or one square up. It can take diagonally forward on the same board, by going one step left or right plus one step up, (for instance, d4xAc4, d4xAe4), or by going one step straight forward plus one step up (for instance, d4xAd5 for white).

A pawn promotes on a square from which he cannot move further, i.e., the twelve squares on the last rows of the lowest and of the highest boards. On the lowest board, the pawns can make a double initial step, and can be taken en-passant there. Castling, and other rules, are as in usual chess.