This game has some great potential is seems to only be held back by that 48-hour time constraint. I really enjoyed the platforming, esp. with the twist two kinds of gravity. The art was also top-notch and very stylistic, and I thought matched the music pretty well.
As others have echoed, I had some difficulty understanding when things would and wouldn't try to kill me, as well as what was triggering the gravity to switch. The first tutorial was awesome and clearly explained everything. I especially liked the double-jump being communicated with a second, smaller space-bar on top. Just do more of that, please (if you had time, that 48 hour limit is rough haha). Just something pointing to the timer in the top-right on the second level, or some text saying that you can't collect the key until all the enemies have been killed would go a long way, or that health packs only actually heal you in certain gravity.
But that's all polish, and what you made in the time limit is awesome. With some more time to expand the tutorial and such, I could see this game doing very well.