Chess4D

Chess4D is a free browser chess site with three modes. 4D chess is played on a 4 × 4 × 2 × 2 hypercube board (64 squares) with X, Y, Z and W axes and legal-move markers, against a practice computer or a friend on the same device. 3D chess is standard 8 × 8 chess on a rotatable 3D board, played against Stockfish or two-player on one device, with move history and undo. 5D chess is an independent, experimental time-travel variant with branching timelines for two players sharing one device. Step-by-step rules and five guided 5D lessons are included. No download or account needed to play.