Counter strike 2, released recently and runs on Linux, I can't say that the people you'll meet on that will be that great all the time, but you may be able to meet people there.
You might also be able to meet people in RuneScape or old school RuneScape, or other MMO type games, usually they have clan features where you can join a group of players.
Not sure if it's still busy with players but kingdom of loathing also at least used to have players you could chat with live, and could join a clan or something like that in there.
This sounds like a good book to me, really hope you find it again as I know what it's like to vaguely remember some show, movie, or book from years ago and not know what it was called or how to find it again.
Definitely would love to read it if you find it, that sounds like a great book.