Just bad planning
The technical limitations of this game are quite large... which makes it reek of sub-par game planning. There just isn't physically enough space to maneuver your germs to keep them alive. For a very long time you can only really infect cells as fast as you can click, keeping your count low. This occupies ALL of your active time, and doesn't allow you to save any germs that float offscreen (killing them) which happens more often than not considering the speed at which they automatically travel in a random direction.
There just isn't any room for skill in this game at all, and several levels are simply unwinnable with certain evolutionary combinations. For instance if you don't yet have the 3 germ at a time reproduction rate, it's nearly impossible to complete the first "make 22 germs at a time" level successfully. I tried for about 20 minutes before giving up and re-doing the evolution (which thankfully I could afford) which allowed me to win in one try.
Didn't you play this game yourself and tweak it before releasing it to the masses? These kind of fun crushing flaws should have been easy to spot and correct. More room to work, slower virus movement, or viruses that bounce when they reach a boundary could have alleviated a lot of trouble.
PS: I didn't enjoy the ultra colorful level much either, it made my screen lag and just hurt my eyes.