Troll Sudoku — It's a real sudoku. Mostly.

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Warm-up: solve one clean board to unlock your first troll. No trolls yet.

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AppearanceAuto follows your device. Or force Daytime or Nighttime.

Auto marksShow every legal candidate in each empty cell. Auto singlesFill a cell once it's down to one candidate, within its block. Smart number padWith Auto marks on, grey out pad keys that can't go in the selected cell. Shake to undoOn a phone, shake the device to undo your last move. Also Ctrl/Cmd+Z.

Notes button: with Auto marks on it crosses candidates off a cell; with Auto marks off it pencils them in. Multi‑select (or dragging across cells) lets you cross a candidate off several cells at once.