It looks cool and if you keep working on it as you said after the jam, it could be a cool game.
Some music would be cool and maybe sounds when you kill or attack. I've only heard the sounds of the gun.
Another cool thing would be some kind of tooltip for example on the gun. I've been walking around it and didn't find that I can use it till I tryed to use the hammer there.
So keep going, it can be a good project!