The graphics are decent. That's something of a saving grace.
We've all seen this style of shooting gallery game before. If you want to stand out, you need to seriously blow my mind and this didn't. A few notes that stood out:
Being unable to switch weapons while reloading can seriously screw players, especially in the early game when they've had no chance to upgrade reload speed. This turns into an astronomical dick move when your game also automatically reloads upon attempting to fire a spent weapon. That is not a convenience, get rid of it.
Introducing enemies with clearly open-faced, improvised helmets that are nonetheless immune to face/throat shots, then later giving us enemies that require face/throat shots gives an impression of lazy design. Fix that too.
The teammate AI is absolutely atrocious. It shouldn't be that hard to at -minimum- program them to prioritize closer targets instead of trying to snipe while there are enemies right in your face. It shouldn't be much harder to tag enemies and weapons with a few basic flags by which NPCs can recognize which targets their weapons are totally inappropriate for - instead of trying to headshot a cop at sniping range with a shotgun, while unarmored targets are right in your face.
Your scoreboards don't appear to be separated by difficulty modes, which makes them kind of meaningless. The game also seems to allow a nearly-unlimited ability to grind for points in levels you've already finished, which kicks out whatever shred of credibility the scoreboards had and makes them literally meaningless. (I just placed third, incidentally)
The range/damage scaling on most of the early weapons felt just excessive and unreasonable. This can persist as an issue into midgame on levels that go really wild with headshot-immune targets, since even midgame weapons mostly need to headshot to be effective at anything but point blank. Moving that line back even a half inch would make a really nice difference.
I do dig the variety of weapons. Various phases in the game actually showcase meaningful differences between them rather than one being an objective upgrade in every way over the last, which was pretty cool. It would have been nice if the grenade launcher had a large enough radius to actually be useful. Dropping a powerful weapon early game but limiting its ammo to prevent abuse is a nice idea in principle but as implemented, the AoE is barely large enough to drop two targets standing shoulder to shoulder. I got almost no use out of it, which is a pity. It's a cool gun.
Any or all of the above would do a lot to make this feel more polished.