The classic, for stakes — and the contract itself is the referee: every move is checked on-chain, three-in-a-row pays the pot to the winner instantly, a full board refunds both. No disputes possible. X moves first; each move lands in the next block (~6–12 s). Stalling can't steal — a silent opponent only voids the game and refunds you.
Your key never touches this page — signing happens in your wallet at get.nadochain.com, then you bounce back.
Every move is a signed transaction bound to its exact turn number — replays and stale retries bounce off. The contract enforces whose turn it is, that the cell is free, and detects three-in-a-row itself, paying the winner in the same instant. A full board refunds both stakes automatically. If your opponent walks away, the move clock (~30 min) lets anyone refund the game — stalling only ever voids, never wins.
Same game vs the computer: nothing touches the chain, no wallet needed. For real stakes, use the game above.