Excellent demo. I had some suggestions like some supplementary dialogue at the beginning of the game (like a coffee sip or an assistant fiddling with the lights), but otherwise it was very fun. Also, it'd be nice if the gun was more prominent! Right now it's a bit small on the screen, and the core game mechanic is focused on the gun, so IMO it should be well detailed and be prominent on the screen.
Can't wait for the full release!