a co-op horror game.
the indie game industry is seriously lacking in that department
There's actually a legitimate reason for that. While it could be fun in the right experiences (Dead Space 3, for example), there's a problem. Dead Space in general is actually a good example, as well as Amnesia and such games.
They're so scary because you're ALONE. Amnesia terrifies you because you're in this dark, decrepit castle being hunted by God's know what, and you have no one to help you, no one to talk to, no one to keep you sane.
The first two Dead Space games were terrifying because there were either very few, or quite often no people that were in any condition to talk, let alone help. They were pretty damn scary. Dead Space 3 I can barely consider a horror game because there are so many other people. It's almost just another shooter with super zombies. But that's just the horror element. The rest of the game is great.