Addicting Game
This game is very addicting. It reminds me of the game Flow (Google it if you don't know what I'm talking about). Did you get the idea from that game? There are a lot of similarities, like eating enemies' parts to grow, warping through worlds, evolving into different shapes, etc.
However, shooting in this game was a bit difficult compared to eating in Flow. The enemies have a pretty high AI in this game, so while they are off screen, they can easily dodge our semi-random shots. It's good to be different, but the slight difficulty made the game less addicting.
Also, the evolving graphics could use some work. Since they looked kind of similar, it seemed like there are only 2-3 shapes you can achieve. It'd be great if you can add more varieties at the beginning levels to keep players hooked.
Sorry for comparing your game to Flow. But in my opinion, Flow is the perfect game, and your game reminds me of a sequel or tribute to it.