Nurikabe is an addicting logic puzzle game with elements of Go and Minesweeper, invented by the creators of sudoku. Build a wall that divides the board into areas given by the numbers — there's only one way to do it!

1. 500 puzzles, 100 of each size
   

3. Difficulty from tricky to fiendish
   

4. An animated guide to how to play and solve
   

5. Unlimited undo
   

6. Subtle visual hints alert you to problems
   

7. Game Center scoreboards and achievements
   

8. English, German and Japanese translations
   

There's a Facebook page for occasional notes and news.