Thanks to NASA missions, we now think that most stars have planets, which means there could be tens of billions of solar systems in our Milky Way galaxy alone. Some have multiple stars, some have Earth-like worlds, some have giant worlds. But the basic rules are always the same: the combined gravity of the stars and planets must allow them to form stable orbits if they're going to last. In this solar system simulator players can create their own solar systems with multiple stars and planets. You can also add comets and asteroids to your simulation.

How does this work? Gravity is universal. It isn't just the star that pulls on the planets: the planets pull on each other, and the star too. This game simulates a solar system by adding up all the pulling for a single moment in time. It then calculates the resulting tug on each object, moves them, and repeats. By doing that many times a second you can see how your solar system evolves.