The thing that stood out the most to me immediately was the music – it set the atmosphere perfectly. At first I wasn’t a huge fan of the floaty controls, but they definitely grew on me over time, and the level design was definitely made with those in mind.
One thing I never grew to like, however, were the instakill pits / spikes / things-that-eat-you. Very few other things actually deal damage, and instantly dying from missing a single jump kinda (in my opinion) invalidates the point of health upgrades.
It was also a bit unclear as to exactly what some pickups did. I never figured out how many hearts led to an extra health, nor did I ever find out what the other green orb items did. There was some slight confusion on what the difference between the area-specific sigils and the five major ones for the end room was, but that did get cleared up eventually.
The artwork was great, the bridge scene with the logo moon in the background was absolutely stunning, as was much of the other environmental spritework. Fun game, great vibes!