Visualy speaking, I love where it is going.
Controling the player becomes frustraiting. It gets very hard to control your movement while in the air, jumping starts being a problem where you cant really tell how far you'll go, specially while on focus mode. It gives a feeling of floatiness, where you lose maneuverability.
Sometimes it feels like the game doesn't register when I press jump, making walljumping feel like chance.
The player tends to blend into the background too much. the ambience in general is pretty dark, making it kind of hard to see all the elements. It doesn't help to differentiate the different kinds of blocks, making the regular and the disappearing ones look similar.
Minor complaint, it feels like the DEAD screen lasts a bit too long, long enough that it becomes annoying.
I guess the major complaints are bad movement and visibility.
I do want to repeat, I really like how it looks. Neon colors, glitchy looking, pixelly, it's really good aesthetically. Soundtrack is quite fitting, enjoyable (I like the little pop-up showing what track is playing, nice touch).
It's a great proof of concept, a lot of nice ideas, that need a lot of work.
I do wish to see a more polished version in the future, it could be a genuinly enjoyable experience.