Cuz gog store page says only single-player but both Wikipedia and Steam says it has multi-player. So which is it?
If its wrong GOG should update their page accordingly.

There are no more active servers left.
You can use gameranger or link up through VPN with your friends and THEN you can play against one another with one running a local server instance. This goes for a LOT of games..

Why I get GoG their statement in not supporting it is, it is not impossible to get running.

I wish GOG would cut a deal with GameRanger to support multiplayer on old games without hassle (e.g. work some system out where gog login data are also valid GR data).