One Sudoku grid. You and a friend. Both solving it at the same time.

NO ADS. Not a banner, not a video, not one that appears "just this once" between games. Kosudoku has never shown an advertisement and never will.

Kosudoku is Sudoku as a live race. You and your opponent get the identical board and fill it simultaneously — their guesses appear on your screen the moment they make them. Every square belongs to whoever solves it first. Hesitate on a cell you'd worked out, and you'll watch it turn their colour.

That's the whole game: a shared grid, a running scoreboard, and the pressure of knowing someone else is looking at the same empty square you are. Add a friend, build a head-to-head record, and settle it again tomorrow.

RACE HEAD-TO-HEAD
You and one friend on a single shared puzzle, live.
See every guess they make, the moment they make it.
Claim a square by solving it first — it's yours, and it's gone.
Wrong guesses cost you points, so speed alone won't win it.
Track your head-to-head record against each friend you play.
Up to 4 players when you can get a group together.

BUILD A STREAK, HUNT THE BONUS CELLS
Chain correct answers to raise your streak multiplier.
Gold cells double your points. Rainbow cells triple them.
Land a streak on a bonus cell and the score jumps.

PLAY SOLO ANY TIME
Four difficulties, from Easy to Expert.
Chase your own best times and scores.
Every solo game still feeds your league points and rank.

CLIMB THE LEAGUES
Weekly league groups of up to 20 players.
Finish top three to promote — slip and you drop.
Ranks run Bronze through Grandmaster.

PUT SOMETHING ON IT
Wager Quickets on a match. Everyone matches the stake, winner takes the pool.
Earn Quickets from wins, streaks and daily rewards.
Spend them in the store on board skins, themes, fonts and player colours.

PLAY WITH FRIENDS
Add friends, see who's online, challenge them directly.
Schedule a match for later and get a reminder when it's time.
Chat in the lobby and mid-game.

CROSS-PLATFORM
Kosudoku is fully cross-platform — iPhone and Android players compete together in the same live matches, leagues and leaderboards. Challenge any friend, whatever they play on.

NO ADS, EVER
Kosudoku is completely ad-free. No banners, no interstitials, no rewarded videos, no "watch an ad to continue". Your board is never interrupted.

Free to play and ad-free, with optional in-app purchases.