"Heyawake by Nikoli" contains 50 Heyawake puzzles.
"Heyawake" is a puzzle in which you fill in the spaces according to the rules.
It's called "heyawake" ("split rooms") because the face of the board is divided into rooms. This puzzle first appeared in 1992, but a plethora of solutions have been developed, allowing for a very progressive puzzle. Each time you discover a new strategic move, your skills of solution will improve. To ensure your long-term enjoyment, there's a "Stage Clear" mode and a "Random" mode. In "Stage Clear" mode, you progress by clearing puzzles one by one, and in "Random" mode puzzles are generated at random.