It had some sort of an online system but it's long dead obviously. You can play it on LAN through. Remember how it used to be a thing and you could play MP without logging into some external system.
Bad thing is through it's just the same maps you get for "skirmish". Some fags made more maps and it should be possible to make it work, I used some custom maps for skirmish but haven't tried MP. I think you can set a bunch of victory conditions other than destroy others, but competitive B&W is just not that interesting. From what i understand back in the day when people actually tried it it just devolved into throwing fireballs across the whole map until someone gives up because regrowing pop is slow and wood is limited.
You can coop and run with a pantheon. Only the first player gets to bring his creature though. I've done that and it's pretty comfy.
Lastly, as with any P2P game with a complex world state, especially ones from that era it's prone to desyncs which puts a damper on the whole thing. There is a way to restore the game after crash/desync and it sometimes works. Can't save the game otherwise. Well from what i remember, you can load up a MP save, but it will just load in SP, but at least you could look at what you built>>710896
So i wasn't just me who did that. It's a really comfy game, it's basically made for roleplaying Rolf the carpenter marrying his childhood friend.