Moodoku

Sudoku logic, without a single number in sight.

Every board is a grid split into colored regions. Put one cow in each row, each column, and each color — and never two side by side, not even corner to corner. That is the whole thing. It fits in a sentence and takes a few hundred boards to get good at.

If you have played LinkedIn’s Queens, you already know the rules. Moodoku is the same one-per-row, one-per-column, one-per-region puzzle — the type puzzlers call Star Battle, and the one The New York Times prints as Two Not Touch. Every Moodoku board is our own, generated on your device. Happen Labs is not affiliated with LinkedIn or The New York Times.

There is always exactly one right answer, and you can always reason your way to it. No guessing, no dead ends, no boards that only work if you get lucky. If a puzzle can be solved two ways, we do not ship it.

Moodoku is free to play, works with no signal, and needs no account. It is made by Happen Labs, an independent studio building mobile games since 2013 — see the rest of our games.

Tap once to rule a square out. Tap twice to put a cow there. Ruling out is the real game — the cows are just where the reasoning ends up.

Get one wrong and you lose a heart. Run out and the board resets — but the board never changes, so your second go starts from what you worked out, not from luck.

Getting one wrong is part of how you learn. Put a cow where it cannot go and the conflicting row, column or neighbour lights up, so you see the rule rather than just the penalty. Hints work the same way — they explain the next deduction instead of quietly filling in a square, which is the difference between finishing a board and being able to finish the next one. Four boosters — Hint, Reveal, Freeze and Cross-Blast — are there when you want a nudge.

New deduction techniques arrive one at a time, each explained in plain language when you are ready for it. Later boards are not simply bigger — they ask for a way of thinking you have just been shown. Boards are generated rather than hand-authored, so they do not repeat and you cannot solve one from memory.

Early boards take a minute or two. Later ones take considerably longer, and there is no clock on any of them — put the phone down mid-puzzle and the board will be exactly where you left it. What you are really playing for is the moment a square you have been staring at turns out to have only one possible answer. Then the next one falls, and then the rest.