Nice entry!
The concept of a puzzle rpg is very interesting, I like the game idea a lot.
In my opinion, the controls need to be reviewed a bit. Since I can't control the cubes precisely, I've found it more effective to create as much chaos as possible, hoping they merge. Also, sometimes even when cubes of the same size touch, nothing happens; it's a bit inconsistent.
Also some music can really help to set the mood :)
Overall it was a good and creative entry, good job.