Select a game mode to start
Classic: Standard Tic-Tac-Toe on a 3×3 board. First to 3 in a row wins. Draws are possible.
Sliding: After placing 3 marks, your oldest mark disappears on your next move. Draws are not possible.
Expanding Rounds: Best of 5. The board grows each round (3×3 → 4×4 → 5×5...). Win by getting N in a row on an N×N board.
Two players on one device take turns on the same screen. It is the only place you can play Classic tic-tac-toe here alongside Sliding and Expanding Rounds, it needs no opponent online, and once the page has loaded it does not need a connection at all.
Two-player play on one device offers Sliding, Classic and Expanding Rounds. Classic is ordinary 3×3 tic-tac-toe — three in a row, draws possible — which is useful for teaching someone the basic game before showing them a variant. Expanding Rounds is a best-of-five series where the board grows each round, so a session on one device has a natural arc rather than ending after one game.
Sliding is much easier to explain sitting next to someone than over a text description: you place a fourth mark, their oldest one disappears, and the idea lands immediately. Because both players share one board, you can talk through why a move was a mistake as it happens — which is something online play cannot give you.
Matches on one device run entirely in the browser with no server involved, so once the page has loaded you can keep playing on a plane or with no signal. Nothing is rated and nothing is recorded to the leaderboard.
Start with Classic if either player has never played tic-tac-toe at all — it is the game everyone already knows, and it makes the variants easier to explain afterwards by contrast. Pick Sliding for a quick session where you want the twist immediately; single games are short because draws cannot happen. Pick Expanding Rounds when you have longer: it is a best-of-five where the board grows each round, so the difficulty ramps and the series has a real ending rather than stopping arbitrarily.
Both players use the same board, so the only etiquette needed is handing the phone or laptop over after each move. On a touchscreen this works better than it sounds — the board is large enough to tap accurately one-handed, and because each turn is a single tap there is no fiddly input to get wrong while the device changes hands.