I mentioned this to Mort a while back as I figured it would appeal to him but now the older versions of Space Engine are free to download.
https://youtu.be/nq8YsgGghDc
http://spaceengine.org
I've always liked playing around with stuff that lets you wander round on an epic scale. It's a different timewaster but one of the reasons I play Elite Dangerous as much as I have (aside from the nostalgia aspect) is that it uses a full sized model of the Milky Way as the play area so once you have a basic loadout fitted you can just pick a direction and go see what you can find. That game has been running for a little over 5 years now with thousands of players and they have explored less than half a percent of what is there. So I can see myself playing around with Space Engine for a good while yet before I buy the latest version.