Ultimate XO

Tic-tac-toe you can actually think about.

Ultimate XO is nine small boards arranged in a big one. Win a small board and you claim its square. Win three of those in a row and you win the game.

The catch is what makes it a real game: the square you play in decides which board your opponent has to play in next. Every move is two decisions — where to go, and where you are willing to send them.

THREE GAMES • ULTIMATE — nine boards, one game, no two matches alike • CLASSIC — the 3×3 everyone knows, for a quick round • MISÈRE — 3×3 where three in a row LOSES. Harder than it sounds: only one opening survives a perfect opponent, and it is not the one you will try first

AND PLENTY TO DO WITH THEM • DAILY CHALLENGE — one position a day, the same for every player. Solve it and keep the streak • THE LADDER — twelve opponents in order, from a first game to the deepest search in the app • BLITZ — put a clock on it. Five minutes, three with an increment, or one • FOUR DIFFICULTIES — from a gentle first game to an engine that does not blunder • TWO PLAYERS — pass one phone back and forth • ONLINE — play a stranger, or send a friend a room code • ACHIEVEMENTS, RECORDS AND BOARD THEMES

No accounts to create and no sign-in wall. Play offline whenever you like. The game is free and supported by ads, which appear between games rather than during one.

Classic and Misère on Master are genuinely unbeatable — both are solved games and the engine plays them perfectly. The best you can do is draw, and in Misère that draw is hard to find. Ultimate on Master is a deep search rather than perfect play, so it can be beaten. That takes some doing.