Outsolve your Sudoku rival.

Play Sudoku head-to-head online. SU2KO gives two players the same puzzle and the same clock: first to solve it wins, three mistakes forfeit. Free, no sign-up.

How SU2KO works

SU2KO is a free online multiplayer Sudoku game. Two players get the same puzzle at the same moment and race to fill every cell. The first correct finish wins the duel, three mistakes forfeit it, and every rated match moves your Elo rating, which starts at 1000.

  1. Press Play. SU2KO pairs you with an opponent of similar rating in seconds. No account needed: you can play as a guest right away.
  2. Solve the same grid. Both players see the same Sudoku and the same clock, and a live lead bar shows who is ahead.
  3. Win the race. Fill every cell correctly first to win. Three wrong entries forfeit the match, and a match caps at 30 minutes.

Questions

Is SU2KO free?

Yes. SU2KO is free to play in the browser, with no download and no account required. Guests get a rating and a match history on their device; registering keeps them across devices.

Can I play Sudoku with a friend?

Yes. Press Play a friend to create a private room, share the six-character code or the link, and the match starts as soon as they join.

How does the rating work?

Every player starts at 1000. Rated duels move both ratings by an Elo formula, so beating a stronger opponent earns more. You appear on the leaderboard after five rated games.

What happens if I make a mistake?

A wrong digit counts as a mistake. Three mistakes forfeit the match, so accuracy matters as much as speed.

Can I practice alone?

Yes. Practice mode gives you a solo puzzle with the same board, notes and assists, and it never affects your rating.