I like the idea here!

I hit some sort of glitch, I believe. Unfortunately I wasn't paying attention to the round, so it could conceivably be by design, but near round 12 or 13 an infinite wave of every robot showed up. Computer choked a lot and I could throw an endless wave of footballs through the slowdown. Ultimately, the robots were working with a greater infinity.

Good beginning.

There's a lot to commend here; good graf, nice sounds, interesting upgrade structure. A few things that might improve the score: stating when the final upgrade has been met, on-screen ammo/reload meters, maybe a more comlex scoring structure (with chain combos, headshots and the like). I also had trouble hitting one of the small, orb drones on wave 12: a small bug perhaps? I could hit all the others before and after with no trouble.

too...

simple, but a okay game nonetheless