MAP30: The Lair (Doom 64)

MAP30: The Lair is the thirtiest map of Doom 64 and the second secret level. It contains the same stormy atmosphere and chilling BGM as Level 12, Altar of Pain. This level consists of a medium-sized structure with an upper, open area and a winding basement that houses demons of varying degrees of strength and, for all intents and purposes, this is where the player will first come across Arachnotrons. Like Outpost Omega, the main mission in this level is to find the demonic Artifact, 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 Artifact. After this is accomplished, the player must then continue through the building into the basement, battle hordes of demons, and find the yellow key, which gives you access to a switch which will bring about the exit, which is back in the starting room.

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 his 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".