umber Duel is a free browser number strategy game. No signup, no ads, any device. Pick a number (0–9). Two numbers combine to hit a target — sum or product. Claim the matching cell on a 5×5 board, connect four in a row to win. Fifteen Duel: claim numbers 1–9, make three that add to 15. The winning triples map to the magic square — tic-tac-toe with a math twist. 3 modes • Bot opponent • Multiplayer via link • Daily challenge • 5 languages