Oh I love 3d platforms with nostalgic visuals like this! Here's some things that I noted:

Visuals: The color palette is really saturated and vibrant , it gives a unique look but it's very hard on the eyes ( especially the checkerboards floor). You should have played with contrast ( ground darker and background lighter, or vise versa).

Controls: The jump input is usually missed, my input is not registered when I press space while moving I always have to stop. Also the jump needs an input buffer and coyete time ( google those terms, they are a life saver!!) and the jump should be slower when you go up and faster when you fall down ( That's not how physics work but it makes the jump 20000% feel better)

Enemies: Damn they so fast, you should be careful to not make enemies faster than players and have more health than player ( unless it's at the end of the game where the player is experienced). At some point I was stalking an enemy from behind and they jumped at me and scared the hell out of me lmao.