I'm a huge fan of flash horror, especially the kind of urban-legend making stuff that you can find via CreepyPasta or the SCP Foundation. They've spawned a multitude of boogeyman for the new generation, whether you like your monsters tall and well dressed or if you prefer them a bit on the existential horror side. I also love video games. If game designers were looking for ideas in that particular direction, they would definitely have a mountain of gold to sift through.
It's no surprise, then, that stories such as The Slender Man mythos gave birth to ongoing (and chilling) projects such as Marble Hornets
Now efforts like these are all well and good in their slow-building terror (which they do very well, thank you very much) but I like my pasta a little more interactive. Which brings me to my list:
The concept is almost ridiculously simple: Walk down some stairs. And keep going. And going. And going. It's pretty creepy and dark, I guess...kind of rusty and dirty. A few eerie noises and-what was that? Oh SHIT....Oh God, what the hell is that? Ohgodit'sstaringatme D: AH SHUTTING OFF NOW.
The predecessor to the presently popular alternative, Slender,
Slenderman is really more Silent Hill meets Resident Evil. You are
tasked with exploring an eerie building while trying to navigate around
the aforementioned boogeyman and his minions while collecting items.
Having played this, the atmosphere is not quite as powerful as the other
games on the list; mainly because the tension is reduced by granting
the player the ability to shoot Slender Man upon encounter. A savy
player will be warned of his impending appearance via static
LSD Dream Emulator lives up to the very definition of its name. The game is themed around one of the most potent hallucinogen known to the public and its very happy to stand behind you peeling off the stickers. From the moment you start this Japanese level of hell, you are at the mercy of its absolutely insane generator, which conjures scenarios like the one above (also known as the face of your deepest nightmares) for a player to explore at completely random. You encounter otherworldly settings, inhuman creatures, and a malicious, dark-cloaked entity haunting you throughout....
The game that will guaranteed you never go into the woods again. Or anywhere. Ever. The premise is simple: search around for pieces of a manuscript while desperately trying to retain the slivering pieces of your sanity...and bladder.
For anyone who has so much as glimpsed the entries at the SCP Foundation, this concept is undiluted, grade-A fearbait. You are an "employee" (and as ever, the SCP takes that very loosely) tasked with assisting during a routine containment investigation...until it all goes horribly, terribly wrong. An entire facility of your most dreaded creatures and artifacts...happy escaping.