Really well done! The action is very satisfying - the shooting, camera shakes, enemies reacting to damage, etc. are all very good!
IMO the difficulty was a bit high but perhaps with some tweaks to character movement that could be mitigated? Using Z to lock character movement was a bit awkward for me - have you considered having the mouse as the direction for shooting?
All in all, this was really fun. I'd be happy to see further progress on this!