Standard chess
Movement, capture, check/checkmate, castling, en passant follow normal chess rules; promotion lets you choose Queen, Rook, Bishop or Knight.
TWO-LAYER CHESS • TUNNEL RULES
Think beyond the next move.
Think through the board.
A two-layer chess variant with Surface and Underground boards, bidirectional tunneling, same-square ambushes, and unlimited cross-layer knight jumps.
2 LAYERS
Two tactical layers
Every piece starts on Surface and may exist on either Surface or Underground within the same 8×8 coordinates.
Bidirectional tunneling
Tunneling down and back up are both legal; a piece may capture an enemy on the matching square of the other layer.
Limited tunneling
Each side always has at least one free tunnel; the maximum tracks surviving pawns across both boards, with no normal tunneling on consecutive turns.
Knight breaks depth
Knights move or capture in an L across layers without limit and without consuming normal tunnel quota.
Free response
Escaping check by tunneling gives the opponent one tunnel response on the next turn without consuming free quota.
Draw rules
Stalemate is immediate. Threefold repetition or 50 moves per side without a pawn move/capture allows a draw claim; fivefold repetition or 75 moves per side is automatic. Two human players may also agree to a draw.