Sudoku Neighbours - 200 Hard to Master Puzzles 9x9 (Volume 4)

Neighbours is played on a grid of irregular shape. Some cells of the grid contain numbers. It is necessary to divide the grid into a number of connected regions of an equal number of cells. Every region contains exactly one cell with a number (or a question mark) in it, and has as many neighbours as the number indicates. Regions are neighbours when they share a part of their border.