[s2l]

Check out minetest open source too, which is similar but separate game like minecraft. You can self-host the server.

[xeonmc]

or, as the kids like to call it, the "We Have Minecraft At Home" version.

[astrobe_]

Tell them they can just call it "Luanti" now ;-) [1]

It's also becoming more and more "not just Minecraft". For instance this entry from the latest GameJam, which is a nice little shooter [2]

[1] https://www.luanti.org/

[2] https://content.luanti.org/packages/Sumianvoice/extra_ordina...