Interesting mechanic, but pretty difficult levels. I had to give up at level 5. Though, level 4 was already beyond the limit. The levels are difficult for three reasons: level design, gravity strength and landing requirements. The transition between different gravities is cool, but also hard. This mainly ties in with the very strong gravity. If you then also require the craft to be landed perfectly up right, then it just becomes too much. Change those things and you have a really cool game on your hands.