I love the graphical style! It suits the game well.
I think I ran into a couple glitches when I played. My first play through, I didn't know it at the time, but I'm pretty sure the faster-firing-speed upgrades were not working as intended. This is because I did another playthrough, except this time the gun was shooting way faster after I bought all the upgrades.
The other glitch was this: upgrading the gun to have the fastest swivel speed actually makes it work quite poorly. It will seemingly start to oscillate trying to lock onto a target, and so will effectively freeze itself for seconds at a time... and not shoot any bullets during that time. This means the last turn speed upgrade is actually a bad one to get.
That said, in my second playthrough, my secret trick is I was actually playing with an autoclicker (it's something I do sometimes with jam games). This was what actually enabled me to level up every upgrade all the way, because otherwise there simply is not enough time to collect all the scrap... so I guess maybe the broken fast turn upgrade is just karma for using an autoclicker. 😄
Actually, this is one of the mechanics I think is really cool. The way that free gears just pile up in the end game... but there's no time to harvest them... it's cool! In the early game you sort of feel like, "come on, give me more ships so I can upgrade faster!" and then in the end you do get a plentiful supply of gears... but one you can never access. It's a fun twist.
In my first playthrough, when I was clicking manually, I found the gameplay loop quite satisfying for a while. It's satisfying to be able to click precisely on a ship, and the way that they go splat, as others have said, is quite fun, and then harvesting them for gears is another bit of precise gameplay that helps add to the loop.
My opinion on the end game is not entirely clear. This is because in my first playthrough, the gun was malfunctioning (oh... how thematic 😉) and not shooting fast enough, so I believe I had to click more than I really should have had to... while in my second playthrough I was of course using an autoclicker and could have gone on forever if I had chosen to, from what I can tell. (I stopped after collecting 1000 gears plus all the upgrades).
That said, my feeling is that the gameplay works out OK when the gun doesn't glitch out. I think that it is a good idea for the ships to eventually overwhelm you, and I think that the non-glitched gun will actually help you for real in the endgame. That is to say: I had a reasonably fun overall gameplay experience with my first playthrough, and I think it would have been even better had the gun actually worked, so I think it works in terms of game design.
Note that I did not figure out at all that it was possible to harvest gears from the scrap until reading some of these comments. I tried clicking on various things in the scrap UI but never noticed anything happening. I think in this case even just adding an instruction on the game page like "scavenge for gears in the scrap metal!" would help players figure out what to do.
I did figure out enough for the game to be playable, though. I liked the core "malfunction" component -- it meant that we had to focus on the precision-mouse gameplay with a long-term goal of repairing the gun. It also gave some interesting tradeoffs--do I repair it now, or try to get the shield upgrade? I personally opted for as many shield upgrades as possible.