In a weird way I did like this game. The art reminded me of 90's shooters so that was awesome. Exploding skeletons, awesome. I'm glad you added a skeleton noise in or I wouldn't have been able to find the last few on a level.
It might help if you put some signs or graphics up on the walls so I didn't keep back tracking by accident. The other would be to make your run mode way faster. It was more like walk and brisk walk.