It's crazy how trippy and almost dizzying that Mario Galaxy trick is in 2D. You got it to work really well, too.
You'll see this in a lot of my comments, but I'm just not a fan of platforming with a mouse as part of the control scheme. For some reason, to me, as natural as it is to move with keys and look with a mouse in an first-person game, it's equally as unnatural to try to move with keys and aim with mouse in a platformer. On top of that I felt like the character movement was squirrely. The jump feel hyper to me, like they're a little too quick. Personal taste maybe, but I prefer having enough time to correct my jumps if platforming is going to be a big part of the gameplay.
Checkpoints would be a good addition, especially near the boss. The Boss Man actually ended my play-through, 'cause I didn't have the patience to go through the entire area again a third time. >_<
Overall, I think this is decent entry. Okay controls, but fun dialog, neat Mario Galaxy effect, and solid aesthetic. Nice work : )