Ok so far it seems like the 10 minute mark would be best haha the thing is its so hard to just stop a video in 10 minutes:/ I am currently upload a 25 min long Gmod video because I couldn't have seen a good spot to cut the video! It is a horror map for Gmod...[DOUBLEPOST=1402396585,1402396074][/DOUBLEPOST]
I saw your vanish game play! You said you were playing with a friend but I never saw him? Is it COOP? I am always looking for good COOP horror games!
Unfortunately no it was not co-op, he played while i sat in the background (i was the quiet voice). Co-op horror games are few and far between :/ there aren't many -.- the closest you'll get are Gmod maps, Beta games like slendytubbies or survivors and a few payed games (which leave much to be desired and aren't really worth purchasing for a lets play)
as for multiplayer games, same as you im always on the lookout for em, as for ones i can think of right now (all free):
- Slendytubbies 2 (not really scary but can be funny)
- Survivors (russian beta, pretty old, does glitch somewhat badly, does require hamachi)
- Hells prison Gmod (judging by the videos ive seen from you im sure you know the gmod maps)
- Minatours maze (also a beta, interesting concept, overall not bad)
The tactic ive been using at the moment is getting friends to play horror games and recording them, that and sharing the game. One player controls the movement (keyboard) the other controls the sight (mouse) can make for soem pretty interesting footage. I do highly recommend Vanish though, its not overly scary but it does have an interesting plot-line and does have a definitive end. (You can "win" XD) its free which is a plus

theres a download link in the description of the vanish video

[DOUBLEPOST=1402409462][/DOUBLEPOST]
I don't believe that Vanish has co-op. The only ones I can think of off the top of my head would be 'Damned' and Gmod Slender. Unfortunately, the horror co-op idea isn't a very popular concept right now, mostly because it's hard to create a good horror environment in a co-op. I can't wait until a truly successful horror co-op comes out, hopefully implanting the idea into developer's minds that it can be done.
I had a chance to talk with the developers of "The Hat Man" back when they were doing trials for the game and i asked them why co-op horror wasn't a big thing. The issue seemed to be 3 main things: Loss of the horror atmosphere, the concept and the programming.
now think about it:
Number 1, the horror atmosphere, you kinda lose an element of horror when you add a second person. In my opinion its true and not true, yes by adding another person the fear level goes down but if you can terrify one person that terror becomes contagious

if anything (if done well) it could actually increase the amount of fear! (but again only if you do it well otherwise the game goes from horror to comedy)
Number 2, the concept, What would the objective be? how would the story work? how would the map and atmosphere work? games like slender are about collecting pages what would the goal be? who can collect the most pages first? i think you lose horror value if you make it competitive. As for Co-op, the enemy or monster your trying to evade how would it work chasing two people? if you got too far from each other it'd end up chasing one person while the other collected pages. Also if there's a story line (and usually there is) how does that second player tie into it? (i'm only using page collecting horror as an example but if you think about it most horror games incorporate finding items in order to achieve goals)
And finally three, programming (and trust me im no expert but ill go about it logically), Most horror games are full of suspenseful atmospheric events, little tricks with monster mechanics (how it finds you, why it follows you, can you hide, things like that) and general map mechanics (randomly generated maze, etc, etc). Monster mechanics would become more difficult with 2 people, it'd either require the monster to chase both players equally or for the game to incorporate 2 monsters. Map Mechanics, if you have a randomly generated map and 2 players they'd always have to be together because if they split too far apart they'd be on separate paths and those paths have the potential to intercept usually blocking one player. it'd be like playing tron with an angry creature behind you (actually not a bad concept XD)
Now i'm not saying its impossible, it just requires a lot of effort a lot of knowledge and a lot of resources, id say that's the main reason co-op isn't as big as single player. Its easier to make a single player horror game than it is to make a co-op and success is much more likely to be achieved with a single player horror game, co-op is a risk
(again this is all my opinion and my perspective

and there are many more points i kinda disorganizedly skimmed through them but i'm sure you get where i'm goin)