A really solid puzzle combination of Sokoban and chess that takes full advange of the logic of both games for some really clever puzzles (mostly). The classical soundtrack doesn't really get old as you can play it on and off and there is a good variety of mechanics to figure out. All the levels have their own jingle even.
The only thing that doesn't quite work is the freezing mechanic that sometimes with undos it gets stuck on a piece and in order to recover it you'll need to restart the level. Nonetheless, a solid option to pass the time.