Very neat, but not exactly pretty presentation. Not fond of the UGUI style giant buttons that aren't animated at all.
I think it might start far too difficult too. Your initial levels should aim to teach mechanics in a simple to follow way, but the first level in this is baffling. I solved it, but it required lots of thinking ahead, which as a new player was pretty tricky. If it had been "make a red 10" and the options had two side by side red 5 tiles, I'd have got it easily and learned something. Two red tiles produce a red tile with the sum on it. The next level could have been "make a red 10" with two 5 tiles, but one of them green.
In that way, you slowly build up the complex rules one by one in your players' heads. Much easier to get started like that!
Congratulations anyway, it's no simple feat to get a working game built in 2 days!