Gravtrav: Gravity Traveller

Gravtrav is a side-scrolling sci-fi puzzle game built on the laws of physics and gravity. You have to guide your ship from one hypertunnel to another, while spending as little fuel as possible. The more economically you use fuel, the more points you will receive for completing. Stars and planets on your way will attract the ship with their gravity. This can either help or hinder your journey, so you'll have to think carefully about your movements.