This is a great concept. Got me addicted and so I kept playing and died on floor 5. I kinda wish you did a little more with the arenas though, since most of them felt the same. Maybe adding more colliders in between would have made things more interesting as well. Also wished you had some other form of visual feedback on the shoot timer since having to look at the timer instead of trying to dodge bullets got me dead each time. Maybe have a circular bar around the player which reduces to show the time left for the next shoot. Either way though, it's definitely a good entry