Book off Demons is a really interesting design. Hack and slash gameplay distilled down so far that it almost resembles something else entirely. Every floor of the dungeon has a track along the floor and your character can only walk backwards and forward along that floor, and you attack by.. clicking and holding on a nearby enemy. It's almost absurd. Yet it has mechanical depth which comes from the range of spells and abilities you pick up as you progress, and the variety in the enemy design that changes exactly how you need to click on particular enemies to take them out. Combine that with general strategy both in your build and the combat, and you've got an unusual game that just works really well. On top of all that the game is conceptually very strong with a really neat visual style holding it all together. Book of Demons is well worth playing.