Shadow of the Wool Ball

Shadow of the Wool Ball is a modification of Doom II, later released as a standalone game using the ZDoom engine. The player takes on the role of a hedgehog, imprisoned by the evil cat army who have also abducted his girlfriend. After escaping his jail cell, the hedgehog must now shoot his way through hordes of cat soldiers to save his sweetheart.

The game was made as a tribute to Wolfenstein 3D and mimics that game in its level design: all floors and ceilings are on the same level, and all walls are orthogonal to each other. However, there are a lot of additional environmental elements, such as fans which blow the player in a given direction, snapping steel jaws, and more. There are also various one-off traps which only appear in one level.