Cute character.
Cute enemies.
Definitely a mechanic that could be used for some interesting puzzles and levels.
However.
Some UI would have been useful. I know you tried to make it work without UI, but being able to look at the corner of the screen and knowing how many DNA I had would have been nice. As well as a clear indication of if I'm the right size to fit inside a gap. I more than once bonked me head on low door ways.
Some more readability and information would have made me give it a better score.(not that I scored it poorly, but you know what I mean lol)