From WPC unofficial wiki


Shade some cells so that shaded sections form rectangles, and numbered thickly outlined regions contain the given number of shaded cells, not necessarily consecutive/joined. Blocks without numbers can have any number of shaded cells. Rectangles must not share sides.

(Rules and example from WPC 2017 IB)

History of the puzzle[edit]

First appeared on Nikoli Volume 122 (2008). Its inventor is unknown. The name Chocona is a result of the contraction of a very long name チョコに国境なし ("no borders for chocolates").

Appearances in the past WPCs[edit]