Very slimy entry (positively ofc). It's already good, but there are so many things you can upgrade to make it even better :D
Theme:
Without a doubt a great theme interpretation. Apart from the obvious one, I liked to think about one more. "Less slimes is more eyes xD"
Visuals:
Great job here. Models are great, slimes are totally cool (I love that they get bigger and get more eyes), animations are fun. You played a bit with particles, and they are also nice, tho you can do some amazing things to improve them. First is I would reduce their lifetime a bit as on some maps you can see how they are falling beneath the map. The other thing I would do is to improve these slime particles with some decals on collision with ground. So that when this green ball falls into ground it creates a green splash sprite on collision (and it changes size to 0 overlifetime), if you don't know how to do it, you can PM me, so I can show you.
The other idea that could be nice, would be a screen shake while slimes collide or fell (just a little screen shake), it might add some weight to them (the bigger slime the stronger shake).
And it would be good to work on a UI, making it more of a cartoonish rather than default and add some postprocessing effects (vignette, grain, maybe color corrections and bloom).
I know that it was for the game jam so, it was not really possible to do much more (you did great job!), but just giving some advices on what you could do if you were eager to work further on the game.
Innovation:
What a great idea for a game, very entertaining and puts a smile on your face while playing :)
SFX:
Music and sounds were great, they blended with gameplay so well, that I even forgot to focus on it :P
Gameplay:
Controls are really fine, sometimes I've mistaken split with next slime, but not really sure how to improve on that.
Game Design:
Very good level design, you teach the player in a right order and interestingly. Every level seems to be unique and while playing I've wondered what next you will show me :)
As for beginning or ending, this game by itself asks for some cute opening and ending, but as I've mentioned before, it's for a game jam, so I imagine it would be pretty hard to do (I enjoyed the ending texts tho :P)
That was a pleasure to play and rate this game. Keep up the good work :)