Interesting mechanics. It looks like your on to something. I hope you continue work on it later.

Pretty fun game , but the art is very rough.

Great idea. Also I died a lot. 

nice idea :) 

a couple of things you may consider when you want to develop it forther:

* during a merge, try to freeze the enemies and / or make the player invincible for that time.
* add more feedback like a short color flash to certain events like "got hit" etc.
* add some basic sounds. this would add a lot.

My experience as a green square is that I die a lot :) I like the merging idea.

I don't quite understand the full mechanics of how it works, but I think the concept seems really cool. Good job.