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.

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.

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.

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.