Islands
Every number is an island of exactly that many squares. Mark the rest as sea: the sea must join up in one piece, islands never touch side by side, and no 2×2 block may be all sea.
How to play Islands
The rules
Each number belongs to an island of exactly that many squares, counting its own square, and every island holds exactly one number. Islands never touch side by side, though corners may meet. All the sea squares join up into one sea, and no 2×2 block is all sea. Breaking a rule draws a dashed outline around the problem and says what is wrong.
How to play
Tap a square once for sea, twice for a land dot and a third time to clear it. Press and hold (or right-click) to put a dot in straight away, and drag to make the same change on several squares at once. On a keyboard, use the arrow keys, then S for sea, L for a dot, 0 to clear, or Space to cycle. Dots are notes: the puzzle is solved once every sea square is marked. Undo takes back one move.
Techniques
A square between two numbers is sea, and so is every square around a finished island. Squares no number can reach are sea. An island with only one way out grows there, three sea squares of a 2×2 block make the fourth one land, and a stretch of sea with one way out flows through it. On the bigger grids, never cut the sea apart, and think through every way an island could still grow: squares they all use are land, squares they all border are sea.
Levels and daily
The 7×7 puzzles need only the first steps: finished islands, unreachable squares, single ways out and 2×2 blocks. Every 9×9 and 10×10 also needs you to keep the sea in one piece or weigh every way an island could grow. The daily puzzle is a 9×9, the same for everyone, and changes at midnight UTC.
Questions
What are the rules of Islands?
Each number is an island of exactly that many squares and every island has exactly one number. Islands never touch side by side, all the sea squares join up into one sea, and no 2×2 block is all sea.
Is this the same as Nurikabe?
Yes. Islands follows the same rules as the puzzle also known as Nurikabe, usually played by shading cells black. Here you mark sea and land, and the puzzles are our own.
Does every puzzle have exactly one solution?
Yes. Every puzzle was checked by a search that found exactly one solution, and solved by a step-by-step solver that uses only logical deductions, so you never need to guess.
Any tips for solving it?
Start with the 1s, whose neighbours are all sea, and with squares between two numbers, which are sea too. Surround each finished island with sea and look for islands with only one way to grow. Hint finds the next step from your position, fills it in and explains why; if one of your squares is wrong, it clears that first.
Is there a daily Islands puzzle?
Yes. The daily puzzle is a 9×9 that is the same for everyone and changes at midnight UTC. Earlier dailies are under Past dailies.