Fun and fresh concept!
I really dig the slot-machine mechanic, It adds that randomness factor that makes every playthrough feel a bit different (kinda like a rogue-like). The presentation is cool overall, the graphics are nicely done.
What I think could be much better is the camera, player feedback and balance overall. The camera angle felt kinda awkward, and the enemies felt very powerful and spongy, while the gun had only 6 bullets and a kinda long reload time. The feedback is little to none, so I didn't have any idea if I was actually doing things I was supposed to be doing, like when getting hit, reloading or hitting an enemy.
With enough polish it could be great! Keep going! ^^