Really solid entry and a strong base to take it further I think. I love the use of the theme as well, fits so nicely with survivor shooters - and to visually see mutations grow on you per upgrade is a nice touch. I think to add a bit more juice to the experience, maybe the movement has a bit of deceleration (a bit of drift) while moving, since it feels like I'm in liquid or a petri dish - organic movement like what you'd see in the older game Flow (for reference).
Great entry and nice play on the theme!