Akiperago ("Archipelago") is a logic puzzle published by Nikoli. A rectangular or square grid contains black cells; some of them contain numbers. The goal is to blacken some cells of a grid according to the following rules:
- The black cells form "islands". No two islands may share an edge; islands may be connected through their corners.
- If an island contains a numbered cell, this number represents the amount of black cells in the island. An island may contain few numbered cells (all numbers will be the same inside an island).
- All islands form "archipelagos". An archipelago is a group of two or more islands, connected through their corners.
- If an archipelago contains N islands, they will be from 1 to N cells (not necessarily in that order).
Cross+A can solve puzzles from 3 x 3 to 30 x 30.