BLDGBLOG: Evil Lair: On the Architecture of the Enemy in Videogame Worlds
http://bldgblog.blogspot.com/2009/05/evil-lair-on-architecture-of-enemy-in.html

Jim Rossignol on the villains lair (nice HL2 and Shadow of the Colossus refs)

Game developers are unconstrained in their designs for the enemy. Such designers will be punished with poor sales, not death in the gulag, if their designs for the overlord are unpopular. They could go anywhere with the homes of evildoers: halls of electric fluorescence, palaces carved from corduroy, suburban back yards.