Submachine/YMMV

Crowning Music of Awesome - The Winter Garden music
Nightmare Fuel - People who have solitude issues or claustrophobia should probably think a bit before playing this game.
- When you play Submachine Network Exploration Experience, the coordinates 666 land you in Hell. Visually it's a small room, dimly lit with red light, with a ladder that you cannot climb to the top of because it leads into absolute darkness... and the audio is loud, intense distortion noises that sound like demons growling and shrieking. Can also be Nothing Is Scarier, given that all the scary stuff in the room is only suggested or ambient.
Paranoia Fuel - Loads of it if you get the sense that you are being watched (the hovering security cameras in Submachine Network Exploration Experience
- Sometimes in later games, you'll be able to visit places you've been to in earlier games and find that things have changed. Some of these changes are because of your actions when you were there before, but then there are... other changes, made by someone or something else, that are not explained. Like smashed lights, broken ladders, added Karma Portals, and Location 747's rubble cleared away to reveal a second corridor that seems to go on forever. The likely real-life reasons for these changes (practical and/or Rule of Cool) may or may not make this any less creepy.