There's definitely some interesting and very well executed mechanics in this, some weird ones as well, like the lighting, it adds some atmosphere but definitely not much else (not saying it's not still cool tho) besides sorta giving a laser etc. for aim.
Otherwise though the shop system is interesting the boss seems quite difficult but predictable which is always very nice to see. The enemies also add a nice crazy element with them coming from all sides, makes it a lot harder to just kite them in a line shooting back, which was by far the default strategy I used.
The upgrade system and the weapon variants seem interesting, though I kept dying before seeing anything past the AR so I can only guess on the power of everything... I want the lightning bolt. I want to see the POWER!!! (I'm assuming it's a lightning bolt anyway). I'll see eventually tho!!!!
Overall though, a really interesting setup, I'd say maybe some more scaling on waves 1-5 and... well I can't comment on the rest so... for now, that's about it. Oh, and uh a bit more feedback maybe on different things I guess?