Thank you all for testing and for the comments!
Nice polished game!
No bug, but the level was escalating too quickly.
I thought it was barely any challenge. I got all the way to level ~25, before the game bugged out. Instead of creating new white cells, it froze the game when I pressed the mouse, so I lost that level.
Sorry about that. It happened when you got the last Size upgrade, I forgot to define the last position on this array
Holy crap, last time I played it "seriously" I got to level 14. I'll try using different strategies to see if get so far, and then I might use the extra bytes to balance things up.EDIT:
I just found one upgrade that was really unbalanced, now it should not get so easy so soon!
PS: reposted applet here instead of the external link because I don't have access to my server at work