Nick, you're the first person to beat the game who I didn't introduce it to myself. Thank you for playing and commenting!
Yeah I've been trying to figure out how they're getting such high scores... It might be a bug I introduced (and not the in-game kind, haha).
I'm working on a paid version now which will have ~20 additional upgrades ~15 additional levels and a campaign. So stay tuned for that.
If you have any other feedback or suggestions I'd love to hear more!