Wow

Wow (also called wow.wad) is a 1999 PWAD by Paul Thrussell for Doom E1M1. It is considered by some to be the worst wad of all time, and it was featured in Doomworld's Top 10 Infamous WADs.

Description
The map is comprised of a single room with a BFG 9000 and some ammo for it. There is no exit, and the main feature of the level is the "illusio-pit": an pit in the middle of the room with a Cyberdemon in it. The pit is invisible until the player falls into it, at which point the screen is filled with Hall of Mirrors effect.