Is it balanced? No. In which way? I beat wave 99 first time playing, and I just skipped all of the instructions. Here are some things I learned throughout my journey:
- When you get fire rate 22-25 (don't remember), you shoot instantly and the enemies die first try
- Wave 24: The upgrades are instant
- Wave 31: The waves are instant
- Wave 79: I bought 999 max ammo yay (it's useless bcs of negative ammo or smth, so I have infinite ammo either way)
- Wave 99: Never ends..

For some game feedback, since all you use is your mouse, why not rebind the fire extinguisher to right click? Then I don't have to use the keyboard at all? And the fire events just never happened for me after like wave 15 or something. My strategy (before I got instakill enemies on fire rate 23) was just hold the shield lever, and do anything else I needed. I really start to wonder how this game was at any point described as difficult, because I got through it WITHOUT THE INTRO INSTRUCTIONS.
Liked the art, and as you said, you should've put more time into balancing it. But deadlines are difficult, and I had the same problem on my game. Good job.