Frequently Asked Questions
Gameplay
How do I play Nurikabe?
Fill cells to create a continuous "sea" while leaving numbered islands. Each number tells you how many white cells that island contains. Islands cannot touch each other (except diagonally), all sea cells must form one connected group, and no 2×2 block of sea is allowed. Every puzzle has exactly one solution.
How do I mark a cell?
Tap a cell once to fill it as sea. Tap again to mark it with a dot (confirmed island). Tap a third time to clear it back to empty.
What tools are available during a puzzle?
The toolbar at the bottom gives you five tools: Undo to revert your last move, Redo to re-apply it, Clear to reset the entire grid, Flood to fill every empty cell as sea, and Hint to reveal a cell.
What does the hint button do?
The hint button reveals the correct state of one cell based on the puzzle's solution. It picks a cell you've gotten wrong first, or an empty cell if everything so far is correct. Each hint costs one hint credit.
How do I get more hints?
You receive 10 free hints each day through the daily check-in bonus. Just open the app once a day to claim them.
Progression
How do I unlock more levels?
Levels unlock sequentially: complete a level to unlock the next one. You can also unlock the next level by watching a short ad. Daily challenge puzzles and shop puzzle packs are always accessible.
Can I view or replay completed levels?
You can tap a completed level to view the solved state, but there is no option to replay it from scratch. To solve a puzzle again, you would need to reset all progress in Settings (which clears every solved puzzle).
What are the board sizes?
There are three main sizes: 5×5 (quick warm-ups), 8×10 (medium challenges), and 10×15 (deep puzzles). The shop also offers 6×6 puzzle packs.
Daily Challenge & Streaks
How does the Daily Challenge work?
Every day at noon (your local time), three new puzzles appear: one each in 5×5, 8×10, and 10×15. Complete all three to count the day toward your streak.
How do streaks work?
Your streak counts consecutive days where you complete all three daily puzzles. Streaks appear on the main menu and on the leaderboard, so you can compare with other players.
Settings & Customization
How do I change the color theme?
Open Settings from the main menu and tap any color swatch to apply a new theme. The change takes effect immediately across the entire app.
Is my progress saved?
Yes. Your progress, settings, and puzzle state are saved on your device and, when signed in to Game Center (iOS) or Play Games (Android), also synced to the cloud. That way you can restore your progress if you switch devices or reinstall the app.
Shop & Purchases
What can I buy in the shop?
The shop offers additional puzzle packs in 6×6, 8×10, and 10×15 sizes. There's also an option to remove all ads permanently.
Troubleshooting
The app isn't working properly. What should I do?
Try closing and reopening the app. If the issue persists, make sure you're running the latest version. If it still doesn't work, contact us at support@nurikabeislands.com with your device model and a description of the problem.
I lost my progress. Can it be restored?
If you were signed in to Game Center (iOS) or Play Games (Android), your progress is backed up in the cloud. Sign in again on your device and the app will offer to restore it. If you weren't signed in, progress is stored only on the device and cannot be recovered after uninstalling.