It is true that there are more than one way of playing Populous online, or better, more than one place. The big problem is that the Populous community is relatively small, and is currently playing in the Populous: Reincarnated service.

 

This community (the PopRE community) is the biggest on Populous, and there are usually between 25 and 70 players online at once. 

 

On the other hand, the PopRES (Wildman production's Populous Ressurection) is another community, which usually had between 10 and 25 members online at once, but in the past years had no more than 8 in their peak.

 

You can also play online on other services, but they probably lack players to play with and against. You can also play using hamachi if you'd like, but why using that when you can play in a matchmaker way easier, with tons of players and new astonishing levels?