Foseruzu ("Four Cells") is a type of logic puzzle published by Nikoli. The goal is to divide the grid into regions of exactly four cells. The number inside a cell represents how many of its four sides are segments of region borders (including the border of the grid).
Cross+A can solve puzzles from
Faibuseruzu ("Five Cells", "Solomon's Keep"): the grid needs to be divided into regions of exactly five cells.