While I liked the sprite art of this game (the player damage animation was particularly good), the RNG of this game just made it a pain. I understand the keys shouldn't drop easily, but one round I killed dozens and dozens of robots and didn't get a single key until 30 seconds left. It hurt my hand with just how fast you have to mash the shoot button due to how many robots you have to kill. They also respawn so fast that, outside of subtle movements to dodge, there isn't really a reason to not just focus fire one of the spawn locations.
The lack of sound also just made the game feel a bit empty.
If the robots spawned slower and the keys spawned either by number of kills or just more reliably, this game wouldn't have frustrated me as much.
Otherwise, nice work!