Some things to look at...
No jumping?
Screen.fullScreen
Screen.lockCursor
Unity has really nice flare assets, use them.
Make yourself a GUISkin.. you need it desperately.
Try and think up something new.. that sets you apart from slender.. I don't know how many of these I've played..
Are you rendering a texture to make it look darker? If so, lower the alpha some.
chill on how often the audio effects are played. Use them to build suspense, not annoy the player.
get rid of the terrain and grass
Things good so far:
audio quality.
Some of the fog effect.
Things fading out of sight.
 "Nightmare Maze"){kind=icon}
Thanks for the input Surgegames!