1. Resident evil 1 (first horror game i played, never forgot couple of scenes)
2. FEAR (i hate that little girl)
3. Half life 2 - Ravenholm level
4. Thief - Deadly shadows (orphanage level - anyone who likes nightmares will like this level)
5. Doom 3 (not one of the best games but that damn flashlight and those creeps jumping from all sides is just a scary combo)
Half-Life 2, Ravenholm, Bloom and full HDR, volume up. Try to stay in your seat if possible. You might need a change of pants if you hear screeching and howling.