Pretty darn decent
While not entirely original, it does make for some good fun. Obviously these kind of shooters and upgrade games don't need to be completely new each and every time. I love the shape evolution that comes with the upgrades at each stage.
Although, I do feel certain upgrades are a little overpriced for the amount of points available each level. It starts off a huge tradeoff - speed for attack rate for health for regeneration. I can only have one. And one isn't quite enough to get me through the levels. Even in normal mode I was struggling.
The thing that irked me was the tradeoff between upgrade points and bonus score. I think that's quite unfair and pointless. I don't want score. This isn't a highscore game. It's an upgrade game. And since the bonuses come in random, sometimes I get more score points that upgrade points. And that serves me better in no way for the next level.
I also think that the enemy speeds are a little similar. Especially the bigger ones. They're movement's are similar and this results in huge clumping once I evade them for too long. And that results in the impossibility of collecting upgrade points further because the infected enemies are in a huge clump next to the still moving ones.
And this is just my personal recommendation, but I think the bigger enemies ought to yield more upgrade points. It just feels right. Killing a huge blob and absorbing it gives the same amount of 'genetics' as some tiny blob. It's quite unfulfilling to kill these bigger ones in that way. Somehow, with more points it actually feels more rewarding. And could help a little towards the upgrades.
And a continue level function would be nice. Or if you think that's too easy, checkpoints at every 2 or 3 or 5 levels.
Overall, pretty darn decent. But nothing too special here.