Nice game, but it hardly fits 2nd PGD challenge theme. The theme of this challenge is traveling between distinct locations. By distinct it is meant that every locations feels completly different (diferent graphics, different music, different level configuration etc.). But after playing your game I only see different level layouts and same graphics.
Don't get me wrong you have already working game all you need is just to chenge it a bit so it will fit into 2nd PGD theme. Man I wish I was on your place and have already working game. But onfortunatly I'm not. I'm still long away from having working game myself.

If you ask me I will do something like this:
1. Change graphics between levels, disticnt bacgrounds, maybe different shapes of object on wich you can move, etc.
2. I would design levels in a way so that for instance fliping a switch in one of them would make some change in another (open you a passageway to another location). I would add several different dorways wich would lead between different levels and alow two way travel through them (travel trough gate only if player presses jump infront of them). This way you could also fit into bonus rule wich requres you to be able to travel back and forth between different locations.
That is just my opinion but at the end it is up to you to decide how it will be done.