If you already own Universe Sandbox ², just run Steam to update to the latest version.
Or you can buy Universe Sandbox ² here:
http://universesandbox.com/buy/http://store.steampowered.com/app/230290/What's new?In Alpha 16.1 we’ve improved the quality and performance of planet and star rendering, improved lighting and shockwaves, fixed issues with saving and loading stars and gas giants, and made a few other tweaks and fixes.
This is a small update as the team gets back into gear after all of our work for the Early Access release and our PAX Prime meetup in Seattle. We are amazed by, and endlessly appreciative of, the overwhelmingly positive reaction to Universe Sandbox ². We look forward to making it even more awesome.
Complete List of UpdatesLet us know what you think! And please report any problems either with the in game feedback tool or by starting a new thread...