Project Highrise might fit the bill - it’s pretty relaxed, and lasts forever.

The standard protocol for friends list and “who’s online” would be https://en.m.wikipedia.org/wiki/XMPP

Like https://en.m.wikipedia.org/wiki/Distributed_Interactive_Simulation or you mean the match-making protocol?

Introversion themselves talked about it at the time
War hospital puts you in charge of a WW1 medical camp trying to allocate limited surgeons, nurses, medical supplies as people come in injured from the front line.
No One Lives Forever is a spoof of Austin Powers, if that gives any idea of the humour level