Nicely done. I like the idea, and the game controls very well. I can imagine it being very pleasing after it's more polished. Background music is nice, it fits the mood of the game in my opinion, and doesn't get very repetitive.
That acid seems only a problem at the very beginning where there's a lot of them, but once I grew bigger, I was far away from them, so that's something that would need adjustment. I like the way acid breaks apart molecules, by flinging them away and not just destroying them.
Minimap is a nice feature for this game to have, well done. Maybe it would be nice if the camera unzoomed a bit when you collect a molecule, so that you can see what's around better.
I think graphics are something were there is a lot of room for improvent.
Well done!