If you don't know En Garde, it's a game based around social climbing in a 'Three Musketeers' style setting.

It's considered a role-playing game, but it's much more like a 'normal' game than most, with a limited list of possible actions, and set procedures for resolving those actions. For example characters (the official version of the rules only allows male characters) can court mistresses, carouse, gamble, fight duels, try to join different regiments etc.

There are many unofficial rules which give extra options such as joining the church, having female characters etc.

Because of its set options, it was commonly played by post (the game was released in the days before commonly-available email).

I'm toying with the idea of making an online version - not necessarily using the En Garde rules, but a new game with a similar theme.

Rather than the usual practice of having a referee who resolves everything 'by hand', it'd be automatically moderated.

I was thinking about each player controlling a small group, rather than a single character - with rules making it difficult for members of a group to directly aid each other - for example a character can't court someone in their own group. Perhaps each group are a group of siblings, or some kind of pseudo-family - I was thinking that the players could play immigrants to a society based around clans, who have to form their own 'clans' to have any social power.

I was also wondering what kind of setting would work best. A 'traditional' D&D/Lankhmar/Ankh-Morpork style city? Something more distinctive?

If I'm understanding this correctly, this game would be very similar to Age of Fable but with a group instead of a single character?  Sounds fun to me.

  A dark fantasy setting would be cool.  Consorting with demons and such could be quite entertaining.

The big difference would be that players would interact with each other.

The idea that magic can make you deformed etc might work well.