At first Accelerant was a kinda confusing game and although its sudden change from 2d platformer to more of a 3d maze kinda game. The platforming design in the first half was kinda fun in some jumps i had to clutch my hardware not thinking ill make it until i realize that i in fact do make it. However the maze half was kinda fun to go through although after dying twice it really becomes a test of remembering where you went and knowing where the enemies are. Besides dying and learning from that the maze is kinda dull as the only obstacles are slow moving enemies that you can even jump over or use to jump onto the walls of the map.
Some areas which could of had more detail or attention would definitely start with some more attention to models, I understand this project is a solo project and i am not a great modeler myself although given the other areas which have much more detail such as the skybox it is clear there is more talent in the 2d department which is why i would then ask why you didn't just do most of the characters on planes and then thicken their z axis to give them more thickness to their look if they aren't facing the player directly.
Seeing it is a first solo jam this definitely isn't a project to scoff at as there is a lot of work that a team would easily chew up on when working in a team, however this project being solo and a first time it is excusable for secondary or tertiary skills to not be up to scratch with some of the more primary skills of the developer. Nice game although some sound choices were a bit of for me and i would of liked a more complete user interface/experience.