Cyberdreams

Cyberdreams is a 1998 megawad by Gonzalo Pèrez de la Ossa and Albert Valls. It is well known for featuring puzzles involving Cyberdemons in each level, which the player is forced to solve without the use of weapons.

Overview
In all levels the pistol and fist are the only available weapons, and nearly all levels require the player to kill the Cyberdemons. Often this is by using clever techniques such as telefragging, activating crushers, making the floor below the Cyberdemon rise so that the height of the room it is in is not high enough to contain it and eventually kill it, and starting monster infighting between it and other monsters. Most levels require the player to activate switches while under fire from the Cyberdemon's rockets (sometimes ridiculously heavy fire), or to dodge rockets while waiting for a crusher destroy the Cyberdemons.