The host picks a puzzle difficulty, how many rounds (puzzles) to play, a time limit per round, and a mistake limit (1 to 10 wrong guesses before a penalty kicks in). Anyone can then join with the room code from the Sudoku Duel landing screen.
Player count decides the whole format: alone in the room, you get a private practice puzzle; the moment a second player joins, the game switches to a shared, competitive grid.
With just one player, everyone gets a personal copy of the grid — nothing is shared or locked, and you can correct or clear a cell freely, same as solving a sudoku on paper. Scoring is tallied at the end from how many cells you filled correctly, not awarded live as you go.
With 2 or more players, everyone races on the exact same grid at the same time. The first person to correctly fill a cell locks it permanently — nobody, including the person who filled it, can change it again. A wrong digit never touches the shared board at all; it just costs the guesser a strike toward their personal mistake limit.
Hit your mistake limit and you're locked out of filling any cell for 12 seconds — your strike count keeps climbing in the background even during that lockout, so repeated mistakes compound the penalty.
Every cell you correctly claim in multiplayer is worth 10 points on its own. Whoever claims the very last open cell on the board also earns a finish bonus — 100 points flat, plus up to 200 more scaled by how much time was left on the round's clock, so clinching the win early in the timer can add up to 300 points on that one final cell alone.
A round ends the instant the grid is fully solved or the timer runs out, whichever comes first. After every round is played, whoever has the highest total score across all rounds wins the game — being first to finish a single round helps, but it's cumulative points that decide the overall winner.
Quick tips
Frequently asked
What happens if I enter a wrong number in multiplayer mode?
Nothing changes on the shared board — a wrong digit is simply rejected and counts as one strike toward your personal mistake limit, set by the host when the room was created.
Can someone else take a cell I already filled?
No — the moment a cell is correctly filled, it locks permanently for everyone, including the player who filled it.
Is multiplayer Sudoku Duel the same as solving sudoku solo?
No — solo mode gives you a private, freely-editable grid, while multiplayer puts everyone on one shared grid racing to lock cells before anyone else does, with strikes and a finish-line bonus that solo mode doesn't have.
Does finishing a round first automatically win the game?
Not by itself — finishing first earns a large bonus on that round, but the overall winner is whoever has the highest total score added up across every round played.
Ready to play? It's free — no signup.