Did anyone ever beat this game?

I am seriously stuck at the 3rd boss creature.

It's a blue cloud with a reddish/lightning core.

I shoot with the blue spit weapon (?) at it, and it splits in two.

Then, the stuff really gets volatile.

Sometimes, I manage to kill one of them, but I always get slaughtered in the end.
Which can not be the meaning of all it.

Am I doing something wrong?