[quote=@Dynamo Frokane]
The GM would be some sort of Contractor who works at the bar, and rounds up a group of skilled individuals to do jobs which will range from vigilante good, to morally questionable. And all these 'missions' will be based around some sort of major murder or robbery. I'd love to bounce some ideas off in building the city with you.
[/quote]

I like the idea of a central Hub area for people to start up and work towards. It sounds like the ideas from Constantine and John Wick where the main character in those (Heh... Both Keanu Reeves) is an exclusive member to those clubs with the outside world not knowing what goes on behind the closed doors.

Talking about the missions, would it be an idea that a player could select their own contracts and maybe venture off on their own for a bit, or work together with another player for a joint exercise. Later on a character could cross paths with another character on a separate mission and choose to perhaps work together to complete it. It might be easier from a GM stand point where the GM is giving the roleplayer the option of what to do in the world rather than telling them, thus they as players can select their own course of action and get developed within their own characters. 

In the end, if done right, you'll have a world with a spiderweb of individual stories that all connect back to this one club, much like a real life situation.