Tic-Tac-Toe is a two-player board game. Each turn, a player adds a mark to a 3x3 board, and the game ends when three marks in a row (horizontal, vertical, or diagonal) are made or the board is full.


Some games are isomorphic to Tic-Tac-Toe.

Pick15 (Number Scrabble)

There are numbers from 1 to 9.

Each turn, a player chooses an untaken number and wins if a subset of his numbers sums to 15.


There are 9 words: eat, bee, less, air, bits, lip, soda, book, lot.

Each turn, a player chooses an untaken word and wins if three of his words have the same letter.

Time Control

Intermissions last up to 30 seconds, ending early if all players are ready.

Each turn lasts up to 20 seconds, with automatic random moves. Unused turn time cannot be carried to future turns. There is only a turn timer, not a game timer.


Turn Time / ms (default: 10000, min: 1500, max: 20000)

A random move will be made after the turn timer expires.

Inverted (switch winning and losing, default: off)

Winners and losers are swapped. Draws and resign/forfeit are unaffected.

Checked (default: off)

This disallows obviously bad moves. If the opponent can win in one move, you are in check. Moves that make you in check or lose are invalid. If you have no moves, you lose by checkmate.

Quick (default: off)

If the game outcome is guaranteed, the game ends immediately. It is not enough for a player to be able to force an outcome; it must be the only possible outcome.

The game outcome can be guaranteed to be a