If you're having trouble with startup, see the basic troubleshooting guide.
If the support team helps, they will likely need to see your log file, so get a head start and follow these instructions to email them your log file.
Experimental builds are unstable builds in development for testing various features, usually for new updates or bug fixes. They may be used to report bugs and help the developers of Universe Sandbox 2, or just for fun to try out new features! You can opt in by going to Steam, go to your library, right click on Universe Sandbox 2. From there, click on Properties. It will open a new tab. It should have a few tabs, go to the right, and you'll see the 'Betas' tab. Click it, after that, there is a drop-down menu that says "Select the beta you would like to opt into". Click the menu, it will open a list of versions you can opt into. There are also earlier versions to play! Click on "experimental", not too far from the top, and let it update!
Note: Experimental builds can mess up some of your objects, please be careful when you use it!
If you can't opt-in, if your game is open, please close it and re-open the menu! You cannot change versions when the game is open.