MAP30: The Lair (Doom 64)

MAP30: The Lair is the second secret level of Doom 64, designed by Danny Lewis. It uses the music track "Lamentation Of The Forgotten". It is accessible from level 12, Altar Of Pain and shares background music with it. This level consists of a medium-sized structure with an upper, open area and a winding basement that houses monsters of varying degrees of strength and, for all intents and purposes, this is where the player will first come across arachnotrons (if the player didn't already go through Level 32, Hectic). The objective of the level is to obtain the Demon Key.

Walkthrough
As in MAP29: Outpost Omega, the main objective in the level is to find the Demon Key, which is located in the center of the building atop a high pillar. In order for the player to get it, he must first head to a closed-off section of the upper deck to the right of the pillar (when facing it from the other end of the room), thereby activating a tripwire that lowers a portion of the far wall, exposing a shootable switch. After shooting it, the player must run to the adjacent section on the other side of the upper area where another shootable switch is located. Shooting that will lower the pillar, giving the player access to the Demon Key. After this is accomplished, the player must then continue through the building into the basement, battle hordes of demons, and find the yellow key. This gives the player access to a switch which will bring about the exit, which is back in the starting room.

Trivia

 * This level possesses a key-activated tripwire, something that has never been used in a mainstream Doom title. The player needs to have the yellow key in their possession to activate the tripwire that will expose the exit-bringing switch; merely walking through without it will result in an "MMPH!" pushing voice and a message stating "YOU NEED THE YELLOW KEY".