Potential could be there...I think it started far too slow (re: the speed option below). It was too easily boring early on. I would definitely suggest having an options menu to speed up the game a bit.
My only addition to the discussion is at the beginning of a 'level.' Too often have I been spawned on top of a radiation cloud. This pretty much leads to instant death and there's nothing I can do about it. Would it be a good idea to maybe add a very short invincibility time when a level starts to avoid this problem?
Similarly, I think it would be fun and interesting if the levels and enemies changed with the environment change. An example would be fighting off cleaning agents and mites and whatever during the house infestation, or amoebas, pesticides, and other fishy eaters in the water stages.
Otherwise, I do enjoy the game. I love bacteria-type evolution games. A lot can be done with this one.
My biggest request would be having checkpoints or something...I hated getting so far only to have to start over when it was difficult/impossible to win. Maybe having a checkpoint every 5 or 10 levels?
Otherwise, I love this game!
I've played it often on other sites and it's one of my faves. A great time waster! I enjoy the concept...definitely different from the usual shoot/defend type games.
I agree with everyone else. Loved the concept and the ability to buy stuff in between levels. If he didn't follow the mouse, that'd be great. And maybe some more detail as to how big rocks could be...although the larger drawing area might fix that. Well done!
Loved the searching for weapons/survivors concept more than anything...definitely unique. I had just a few lag problems toward the end, but I blame my computer. Loved the final weapon. Great game!