I got through, up to getting the ground pound, before accidentally softlocking myself, so here are my thoughts:
1. I like the character's design! The idea that the 'top-half' is disconnected from the bottom, with a whispy tail almost connecting the two is nice! Similarly, I like a lot of the texturing and the visuals. The skeletal pedestals for upgrades were nice too.
2. I had a little trouble with the ground pound jump, and the 'jump higher using it' mechanic. I don't know if i was misusing it, but I had a hard time getting it to consistently trigger (or not trigger). sometimes i would be pressing nothing when i landed, and still 'high-jump'. sometimes I would be pressing jump right before or after landing, and then nothing would happen.
3. I like the idea of the enemies demonstrating variations of the skills the player gets, like the pale ghosts that dash at you. The main enemy I didn't like was the green ghosts, because I always seemed to take damage when dealing with them, and that combined with some difficult platforming led to several respawns
4. I appreciate that 'death' does not force you to start from the very beginning, and that you can select your spawnpoints by visiting them again.
5. Some of the level design feels very hard to differentiate, room to room, which meant if I got turned around, I had a hard idea telling where to go next. Some unique setpieces that are 'facing' a specific way, like a statue or something would probably help with that. Or placing something on the path that makes the player want to go towards it. There was a part of the game after getting the double jump where I didn't quite know where to go, although in retrospect the place to use it was in front of me, to the left, because textures on both the walls and platforms were browns and grays.
6. I have to agree with some of the other members that a dropshadow would really help with positioning, as there were many times where I thought I was above the platforms, only to fall and drop into acid. Additionally, jumps and gravity felt somewhat heavy, which added to the difficulty of positioning and made it harder to tell if I was going to land on pillars that needed it. I did like that the dash let you use it in mid-air, though.
7. Just mentioning it here, because it was end of game and time was probably split as is, but I had a situation where I used the ground pound while dashing, and somehow landed on the ground upside down and 'stuck' in the ground-pounding mode. I could not jump from that point on, and trying to respawn caused me to fall through the geometry of the level and land 'on top' of an arena. This probably is because the respawn does not reset either the state, or the position of the character, so it continued trying to slam towards the ground and slipped through the floor.
Lots of nice stuff here, you all did nice work!