This is really fantastic stuff! Aesthetics and controls are really well done.
I think the only criticism would be that some of the earlier spheresect interactions were a little high difficulty and would have been better suited a little later in the map once the player had gotten used to the controls, as it can be a little fast and frustrating with the laser gate timing needed to reach the switches.
I liked the sparseness of the enemies as some of the platforming is quite difficult and having mobs of enemies would be a little too much and make it overwhelming.
The 2nd boss, the one underwater was really difficult but I eventually saw the pattern but I did almost give up. There's just so much going on in that room all at once it can really hard to comprehend everything that is going on.
I really liked that if you fell in spikes or something that you were respawned extremely close and not all the way back to the last save point. A few more save points wouldn't be a had idea in some areas.
Overall this is fantastic and I can't wait for more. Great job!