Clear the seabed without poking a sea urchin.
Tap to reveal a cell; numbers show nearby urchins. Long-press to flag. Clear every safe cell.
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Reef Sweeper is a free minesweeper-style logic puzzle set on the seabed. Reveal cells one at a time; each number tells you how many sea urchins touch that cell. Use the numbers to work out where every urchin hides, flag them, and clear every safe cell.
On a phone, tap to reveal and long-press to flag. It's a classic deduction puzzle that rewards careful logic over guessing. Free in your browser, no download or sign-up, and your best time is saved on your device.
