It's really well made, but one issue with the game affects everything else.
It's the gun.
It affects the balance, it's too strong compared to everything else, making bots feel not as useful and makes the game too easy.
It affects the sound. The amount of bullets it fires just breaks the sound, and the game gets muted because of it(probably too many sound sources get created).
And most glaringly, it affects the performance. I am on the 27th wave and the game is running with 0.3fps when I fire the gun(level 12) which makes the game impossible to play.
Also the bomb being ready sound effect gets annoying when the bomb gets reloaded in 0.5 seconds.
I think making it a laser or decreasing the amount of projectiles while increasing the bullet damage should fix the problem elegantly.
Other than that great work, and I hope my critique is not taken as an offense.