Quite an lovely game!
Liked the ligthing (maybe I saw you on /r/gamemaker? or was that someone else) and the music a lot. Gamepad controls are a nice touch (haven't read the game page to find out about them, but I had my gamepad lying on my desk upside down with a stick pushed left, so I wondered whether your game was a scroll shooter of sorts at first - silly me).
Enjoyed the weapon pickup system, but I only discovered it after I tried to go exploring - on my first run I mostly just remained in a small starting area. It's a really important system, as without it it'd get stale quite fast - nice that you avoided that.
Once again, the music really fit the mood and when some fairly hellish enemies started spawning, the creepy atmosphere really got to me - well done!