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.
Not in MO myself but I absolutely support this initiative!
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.