Excellent entry. The attention to visual design is really good - with the rocks that need 3 slimes having 3 blocks on top. Similarly with the pressure plates. Numbers or text would work, but you put in extra effort and the result is just great! It's just long enough to explore the mechanics satisfyingly well. The music is pleasant and the sound effects give everything a little more impact.
In the way of criticism - on the level with one slime behind a wall with 2 holes with ite coming through - it's possible to go on the lower side, around the bottom of wall and on the edge there instead of through the small hole, which I think was the intended route. Another thing is that the sound which plays when you fail/ reset the slimes doesn't sound negative enough - the sound that plays when the slimes are split even sounds more fitting. I'm not a huge fan of puzzle games, and I didn't find it super thrilling, but I guess that's not really the mood you were going for anyways. The puzzles weren't that hard, none of them really had me scratching my head (except for the second to last level with the "elevator"). I'm surprised you didn't use that elevator anywhere else in the game, you could've squeezed a level or two more out of the mechanics you've had. Those are however very minor things and you should be proud of making such a good game.