Universe Sandbox has recently been released in early access. It's available directly from the website, or from Steam, GOG, Humble, itch.io and Oculus store. Not sure about pricing from the other stores but, on Steam, it's currently discounted from £24 to £16 for the next 24 hours from the time of this post.

I've only just started tinkering with it, but it seems like a lot of fun if you have even the slightest interest in astronomy (or just crashing planets into one another). It basically allows you to watch various 'What if' scenarios play out, such as 'what if our sun was replaced with a giant blue star with 20x the mass of our star'. You can send our moon hurtling into the Earth, and even cause galactic collisions/mergers.

It also supports VR if you have a headset (I sold mine a few months ago, annoyingly).