fun Idea, I know youre still in the early beta so I know a lot of changes are still going to happen but heres my feedback after playing 20 minutes for some things to keep in mind while you develop the game.
First and most important is that the variance you built into the projectile aim just makes the game less fun, if I shoot and the bullet misses how am I supposed to tell if thats because my aim needs to be adjusted or I just got bad rng? So many times I shoot and think my aim is bad so i make a small adjustment the other direction and then the bullet flies straight the next shot and I end up missing again, thats anti fun, not fun.
Second and maybe less important as this is more just a stylistic choice but the upgrades are expensive and dont feel incredibly impactful. A lot of repetition and grinding from the very begining for very little feeling of reward. If it was an idle game or something I could understand the way the grind is set up but since I have to be 100% active it sort of just ends up feeling like im shooting bullets for no reason.
Third, since the units get stronger as the waves progress but you dont get more money that means its just more efficient to never complete a stage you may as well go to the next stage and just do the first wave or two over and over.
also obviously at some point needs a save function if you want people to properly test the game.