Universe Sandbox where you can spawn massive stars, launch asteroids, and manipulate gravity with just a few clicks, currently Windows only but the developers have said something interesting for the next version.
QuoteThe new version of Universe Sandbox that will likely support Linux is still in development and not yet for sale.
We're developing the new version in Unity 4, so the Linux support should be as easy as the Mac and Windows version.
So it seems again thanks to Unity we will have another awesome game on Linux!
About the Game
Create and destroy on a scale you’ve never imagined with the ultimate space simulator.
Harness the power to create black holes, collide galaxies, and manipulate gravity with just a few clicks. Inspired by the software astronomers use to unlock the mysteries of our universe, never before has astronomy been so interactive or so much fun.
Spawn a massive moon to tear apart Saturn’s rings or launch a rogue star to rip the planets from their orbits around our sun. After unleashing catastrophic destruction, create your own solar system and share it with friends.
Interactive, real-time, n-body gravity simulator
Change any property of any object at any time
Real physics, real data, real units, real science
Compare the objects in any simulation with chart mode
Supports anaglyphic 3D glasses and 3D DLP televisions
Built in tutorials and step-by-step activities
Includes 70+ simulations both real and fantastical
Extensive editing and creation tools make it easy to build your own simulations
Latest version of Universe Sandbox 2.x with Steam Achievements
Thanks to Weltall from the SteamLug IRC for the info.