To be perfectly honest, I have zero experience in this. I’m a writer and currently started working on a horror story that I think would work well for a game. No idea if this is the right place to post this, I only just lightly researched “how to make a video game” and want to give this a shot. I think it would be a cool experience. If you want to work with me on this just send me a message.
People would be more likely to do something like this if they knew what needed doing. What do you need? What can you do? More importantly, more detail is needed than “I want to make a horror game. I don’t have a lot of experience. Please help me.” Stuff like the general plot, base gameplay, etc. is generally what’s needed to win over a potential teammate. Otherwise people would have no reason to sign on. Heck, I might sign on thinking “a FNAF clone sounds great!” When it turns out to be a post-apocalyptic FPS, I might promptly quit since that’s not what I signed on for.
Simply put, refine the concept and post more detail. Also make sure to mention what you can do and what’s needed. Then you might get more than a few people to help out.