Thanks for the honest review, you are of course entitled to your opinion and its totally ok to not like a game! Perhaps I can convince you to give the game another chance though.
Firstly, I'm quite surprised to hear you had trouble with the camera as my camera setup is very standard for most 3rd person games and none of the other raters have complained about issues. Was the mouse movement too sensitive or something? It could be that if you alt-tabbed out of the game your mouse cursor was not captured and that then lead to strange behaviour with the camera?
Secondly, the gun is actually supposed to be a grenade launcher, which means that the projectiles are not meant to travel far (like bullets) but therefore explode damaging enemies and buildings in a certain radius, so you don't have to hit things precisely. So the idea for playing is to fly above the roof (high enough that the enemies can't hit you) and shoot down from above (this will destroy parts of the roof and separate the enemies (ideally onto different levels inside of the building). Divide and conquer! You can keep engaging and disengaging your jetpack to maintain height. Might take a couple tries but once one gets the hang of it, I find it quite fun to rain grenades down from above at the thugs and then go in and finish them off once they are isolated. If your HP gets low you can always jetpack away to regain some health.
I agree that the map is rather empty, there was only so much I can do in a single week and yes I broke the settings button by accident, these things happen in game jams. Loading is slow because the map is generated procedurally and each cell is destructible, there's plenty of room for me to improve performance but I ran out of time.
I'd be really grateful if you're willing to give it another go with these points in mind but if not, that's fine too, no hard feelings!