The game looks really nice.
The puzzle aspect is interesting especially the size that is pretty small so you really have to think about every move.
At first I really had trouble understanding that you had to swap cell. It was not obvious to me that what z was about. I would also say that the game have too many mechanics or special cells because you have to introduce each one after the other and I would have liked few more puzzle in between to get used to each mechanic.
But pretty good game overall. There is a lot of work and polish. Well done!