exactly. i mean having zombies jump out at you is all well and good, but i remember a great part of doom 3 where your crawling through a corridor with loads of pipes and tuff hanging down. you turn the corner and see a monsters shadow, before it quickly jumps away. follow it and your led into a dark room, and as soon as you get into the middle, enemies start dropping from the roof and from behind obstacles. v nice effect. i know its not possible to have monster shadows, but oyu get the idea. just have the player walk down a corridor, and half way down have some sort of noise, something like pipes clanging or footsteps, just to let the player know theres evil about.