This game lends itself to a type of multiplay format that has been around for sometime now.
For those familiar with Civ Game of the Month replays you will know what I am suggesting.

Though there is no true multiplayer implemented for this great game ( btw, I own the GOG version which does not suffer from an issue of not showing tool tips when designing Factions );

There is a multiplayer type challenge one could try vs some friends.

1. Compete using a 'saved file' of the identical starting position. ( true Civ GotM style )

2. Each opponent plays the same map using the same opposition Factions & the same game perimeters, while also using their own Sovereign/Faction designs if they so choose.
There are already some pre-made maps to choose from per this variation, plus one can create & tweak a map per their chosen tastes.

3. Using method #2 one could also submit their Sovereign/Faction designs to be used vs each player per a chosen map/settings.

Anyways, just thought I would share an idea some friends & I have been using as a fun way to compete vs each other.