Fun game, and I have a few suggestions for you for either an updated version of this project or for your future endeavors: I like that the game has no text, it's a cool stylistic choice, but I wish there was some visual indication in the upgrade screen of what the upgrades did. If not words, maybe revising the sprites to show an action shot of what they do (e.g., magnet could have DNA surrounding it with arrows, indicating it attracts them from further away).
Also, I would consider adding an enemy limit, or despawning some after a while, because the game is very difficult with infinite spawning, and my game was slowing down after a while.
I like your theme, and I'd love to see what you do with it down the line!