Pretty cool idea, definitely you could do more with it if you take it further. Apart from the firing being a little slow, I think the gameplay is pretty good. Didn't know there was the room on the left until the plant monsters nearly jumped me, also managed to close the door and locking myself in but I did willingly do that to myself. Could do with making the player movement quicker and more snappy so it's easier to get between rooms, but I guess that a bit of the fun.