Minetest and several others that I play regularly have already been mentioned, so I wanted to shout out a game I've been following and playing for years, waiting for their 1.0 release: FreeOrion

https://www.freeorion.org/

It's essentially a clone of the Master of Orion series, which are classics in the 4X world.

Ugh yeah the official app for Reddit is so bad... I went from using RIF every time I had any time to spare to maybe opening Reddit once a day for a few minutes.

That seems... Not great.

You could determine which XEPs to support...? Also, the usual benefits of hosting your own services. But neither is really a strong selling point IMHO.