very good for what you said you were trying to accomplish, especially when you consider your time frame. the side panels and neverending gameplay with only your soulcount to keep track of the score were all interesting mechanics that made the game chalenging but not so intense that you felt frustrated when you lost.
some things you could add: If your aim is to keep everything real time maybe have some kind of soul accumulation system, like 50,000 souls changes the background or something like that.alternative you could add a store in a pause menu, so the game is still going on. you could also make the devil interfere with the game like have him darken the screen or other times help you somehow so when he shows up you dont know if its a good thing or if hes going to screw you up. Just some ideas off the top of my head. Good job !