Thanks for the feedback! I agree: the game is far too long. With how the spawning works, I'm pretty sure the fastest theoretical time is 1000s since an enemy spawns every second and you need to defeat 1000 to win. Honestly, I didn't put much thought into the win condition. In retrospect, there are not enough upgrades to justify 1000s of mandatory gameplay. I'd consider your 75% a win :)