ReplayChess

ReplayChess turns chess history into something you play. Pick a legend, jump into one of their famous games at its critical position, and try to find the moves they found — against a friend via a private link, a matched opponent, or Stockfish in your browser. After the game you get your match rate against the original and the exact move where you diverged. 50+ legends, 3,600+ ECO-coded openings, real-time multiplayer, installable PWA. Free to play; open source under MIT.