Cool little game, I love puzzle games. I will try to give you some honest feedback!
First off I disliked the music. So as soon as I pressed play and heard it, I immediately wanted to turn it off, but I didn't find the mute-button.You should probably have the mute buttons in game along with in the menu.
I think you should make the google play services optional. Right now it felt "forced" to sign in, and that will put a lot of people off. It allowed me to click cancel, but you shouldn't be asked to log in until you check the leaders boards. After clicking cancel I clicked the leaders boards and it crashed ( I sent a crash report).
The puzzles are very challenging. I think you should train your players with easier challenges before moving on. Lets say that in the start you should only find matching color animals, and as you progress more tiles (and valid sets) are added!
I sometimes forget what combinations I already have done, so if I retry it I think it should give a different "error" than usual. Maybe the 4 squared underneath could flash, so you know why it wont work?
. Thank you very much! 
