Nice game, nice concept, I saw the change of perpescive mechanic pulled off a couple of times for other games here and there, but I don't recall having played a 2D/3D change of view for the game.
While the concept is cool, the game still needs some polishing, for example sometimes I am unable to jump (pressing space bar has no effect) and some other times I get stuk into platforms due to the view/perspective change.
Navigating the 3D scene also feels hard, and lacks a clear way of figuring out the depth of the level: I'd suggest making the camera move a little bit with the payer, i.e. also rotating to look at the player.
Also, adding shadows would help a lot figuring out the 3D layout of the scene.
The game is cool, it could benefit from some game feel adjustments (sounds, particles, animations, ecc...).
Good job :D