Parallel worlds chess

Each side commands two full chess armies on levels 1 and 3.

Each player controls two complete chess armies, initially on levels 1 and 3.

The first player to capture either enemy king wins the game.

All pieces except kings can move straight up or down one level to an empty square.

On levels 1 and 3, moves, captures, and pawn promotions follow the same rules as in standard chess.