Okay, this would be for a PC game. It would be a pixel 2D fighting game with heavy story elements.
General Story:
A girl is sent to a mysterious medical facility that houses different kinds of "summoners", or people who accidentally end up summoning manifestations of their emotions. It is more of an experimental kind of set up rather than the helpful facade that the caretakers like to put up, and there are a lot of odd rules in place that keep the residents from wandering the hallways or contacting anyone outside of the walls.
The girl suffers from OCD, and it gives her a lot of anxiety that ends up turning into small, dark creatures that she has to fight off on occasion. Throughout her stay at the facility, she meets and becomes friends with various caretakers, such as the doctors and nurses, and other patients who have their own monsters to deal with.
Everything is calm, and peaceful. That is, until people at the facility start disappearing. It started with one staff member. Then another. Now even the patients are starting to go missing. The facility tries to play it off as if everything is normal, but even they can't cover up the strange noises at night, and the rumors of something terrible going on within the walls of what was thought to be a safe place.\As tension and anxiety rises, all of the monsters become stronger and more aggressive.
And so the girl, along with her new friends, decide to investigate what exactly is going on by sneaking around the facility and collecting clues, all the while fighting against their inner demons.
I am not experienced with making stories, so please judge the crap out of this so I know what to improve on. If I made something too ambiguous, I'd be happy to clarify what I mean, or give a more detailed description.