Over the course of three weeks, Robert Prest has been working on a Doom (well, Doom 2) mod that attempts to recreate much of the core experience of No Man's Sky.
It's missing some of the fancier stuff around the edges, like a seamless transition from space to planetary surface, but ... for the most part, if you move past the fact the game looks like it came out in 1994 — and appreciate the limitations of working with id's original Doom engine — it does one hell of a job.
There are space stations, randomly-generated planets, weird monsters, even a centre of the universe. And also Bill Bailey, who I never ran into playing the actual game, but who I'm sure thanks to the power of infinite creature generation, is out there somewhere.
If you want to try it out, you can get the files here.