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.
In all levels the pistol and fist are the only available weapons, and nearly all levels require the player to kill one or more Cyberdemons. Often this is done by using clever techniques such as telefragging, activating crushers, making the floor below the Cyberdemon rise so that the room 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 to destroy the Cyberdemons.
Warm Up: One on One -- This level places the player in a head-to-head confrontation with a Cyberdemon. To win, the player must lure the Cyberdemon to the center platform, then move through one of the four teleporters at the corners of the room to telefrag him. This must be done in order to reach the exit, as pushing the switch which reveals the exit activates a trap that captures the player, leaving him free for the Cyberdemon to kill.
The S-2 Factor -- In this level, the player must navigate barriers in order to reach teleporters in order to telefrag two Cyberdemons, while dodging their rocket fire.
A Bridge Between -- To win, four switches must be activated. The player must go back and forth across a bridge flanked by two Cyberdemons, which continuously fire. Hitting the switches will raise the floor sections to activate the sectors that will kill the Cyberdemons. The central bridge has a wallrunning capable sidedef that can be exploited. After going through the platform behind the Cyberdemons, they will eventually be killed, and the exit revealed.
Come on In -- To clear this level, the player must make it to the top of an uneven staircase and trigger a linedef that will raise the stairs to the exit. A number of exploding barrels block the player's path, which means the player will have to lure the Cyberdemon's rockets into each barrel to clear one. Once the player reaches the top, the Cyberdemon will be teleported into a nukage pool.
Cybers and Holes -- The player spawns in an octagon-shaped room, and a gigantic crushing ceiling is activated as soon as he moves. To avoid it, the player must stand underneath one of the three holes cut into the ceiling, dodging the Cyberdemons' rockets until they are killed by the crusher. There is one switch inside each of the holes, and the player must activate them all to exit the level.