No two devils may touch — not even corner to corner.
Marking squares ✕
An ✕ is your own note, nothing more: “I'm sure no devil goes here.” The game never checks them, they cost you nothing, and you can put down as many as you like — they are there to rule squares out and show you what's left.
Tap a square to mark it ✕. Tap it again to clear it.
Drag your finger and every square you glide over is marked in one go — along a row, down a column, or any path you like. Let go to finish the sweep.
Start a drag on a square that already has an ✕ and the sweep erases instead, right along the path.
A drag never places a devil, however it starts — so a stray glide can't cost you a life.
Placing a devil — two ways
DEVIL MODE. Press the button to arm it; it lights up and the board takes a red rim. Now every tap tries a devil. Press it again to go back to marking.
Long press. Leave DEVIL MODE off and simply hold a square for a moment — the devil lands when you have held it long enough. Handy for a one-off.
Nothing else can place a devil, so you'll never drop one by accident.
Taking it back
UNDO steps back through your ✕ marks one sweep at a time. Hold it to wipe every ✕ placed since your last devil.
Devils are never undone — a correct one is locked, and a wrong one is already paid for.
Mistakes
Every board has exactly one answer, and it can always be reasoned out — you never have to guess.
A devil in the wrong square burns the square red and costs a life. Three and the run is over.
A correct devil locks in place, so you can't knock it loose.
Scoring
A flawless board is worth three times a two-mistake one, so care beats speed.
Finish under par and the leftover seconds are added on top.
Each win climbs the ladder: 5×5 up to 12×12, then it stays wicked.
Away from a signal
Add Devil-Doku to your home screen and it opens like any other app, on its own, with no address bar.
The game is kept on your device the first time you open it, so the puzzles work with no connection at all.
Songs and clips are heavy, so each one is only kept once it has played. Pull the lot down now if you're heading somewhere without a signal.
