Oh man, this one was awesome!
First off, that aesthetic. Dithered monochrome pixelart, oh my yes! I love the little details in how the slime's mass moves around from rising to falling. The music is perfect for getting me in a puzzle-platforming mood, and the sound effects are minimal, but everything they need to be.
The controls are a little bit rough - you have very little control over your jump, and you need to be extremely precise with when you activate each poison - but the biggest problem, I think, is how little the game explains what everything does.
Or... is that a problem? Because I still managed to beat it, I had a hell of a time doing it, and there was at least one moment when I literally shouted "AW YEAH!" out loud when I figured out the solution to a puzzle. The fact that the game gives you nothing makes it immensely satisfying when you figure everything out.
I had a blast with this one. Great stuff!