mstdn.starnix.network is one of the many independent Mastodon servers you can use to participate in the fediverse.
Starnix is a Fediverse/ActivityPub Focused platform. Topics are mainly Technology and computer related but are not required to fall into those categories.
That's what I'm thinking because I haven't played through the newer campaigns and the older ones I don't mind either because they also are really good.