What about an entity that is a black, demonic skeleton with red, glowing eyes? It hides in dark areas and it will immediatly attack once your flashlight shines on his eyes. Onced provoked, it will let out a roar then chasing music will pop up. Your screen will start to turn a shade of red once it starts chasing you. There is an escape. You can hide in a locker or if you're gonna add weapons, kill it! When you kill it (if you add this) will drop a red orb thatll do something (don't know yet)

His name will be Darkness or something else. Actually you make the name