Super cool game! I really liked the graphics, although they might contribute to eye strain after a while. The boss fights were relatively easy and it was satisfying destroying the angel rings. However, I was confused for a good period of time because I didn't know how to attack the angels, or where to go. I think having a couple of indicators that mark the open buildings in the world a bit clearer would help. I think the orange guy's boss fight was also a little bit hard, although I'm not that good at parkour, so maybe that's why. Overall, the art and story were super cool and my favorite thing in the game world was the basketball court.
I did discover an interesting glitch in the game, where if the green guy is in his transition phase the timer glitches out at zero, and you are essentially stuck in the world, no white out back to the lobby, and have infinite time to beat the green guy. When I beat him in this state instead of his key Asbeel's key dropped instead, which was weird and then I couldn't find him anywhere in the world after that. So I didn't actually complete the game fully, but I did get pretty far and I think it was quality most of the way. Also, I'm not sure if you intended for the keys of the previous angels to be available in the middle of another angel's bossfight. It's a good way to cut the fight short without waiting for the timer to run out though.