I love it!! It reminds me so much of my childhood for some reason. The 3d environment + 2D characters really gives it a cute touch. The music is on spot for the levels and everything looks so balanced. The gameplay is simple and enjoyable.
My critique could be about the shadows/ lightning involved with 2d characters. Idk, but you could use blending colors that go with the scenery for the player, like instead of just using one black spot shadow, you can make it a directional shadow, that matches the background.
I know it's still in progress but you could make it look a bit more "physical" if you use more colors / textures