The Shadow Dragon Executive Force was actually born as an online gaming clan.
It was the 1999, Team Fortress 2 looked like the next game to be released by Valve and, since the previews were definitely intriguing, it was decided to make the SDXF a clan meant to play this game. It is to note that, at the time, TF2 was presented as a class-based online shooter with a rather relaistic feel: something along the lines of the Battlefield series that came later (Battlefield 2 in particular, because it had a modern-era setting).
While waiting for the release of the game, the SDXF became an active international clan for Team Fortress Classic (considering TFC as a sort of warm up). However, after a few years, TF2 didn't seem to have made any progress on its developement and it became more and more difficult to find TFC servers to play on. The clan, ultimately ceased its activities and in 2003 the Shadow Dragon Executive Force turned into a webcomic (then revamped into its current incarnation in 2006).
In autumn 2007, with Team Fortress 2 being finally released, the clan was rebuilt.

The SDXF is an international clan and welcomes everyone regardless of their gaming skills. The goal is, in fact, to have a friendly group to play with. Winning matches and challenges is a plus, but not mandatory. For this reason, if the clan enters a ladder, tournament or even organizes a friendly match, it will only after hearing the opinion of all clan members.

There are no strict rules, but members are required to act mature all times: rude and offensive behaviour will not be tolerated, nor is purposely causing grief and annoyance to other players (ie. team-killing, killstealing, PK and so on). People who refuse to comform to the above will be banned permanently from the clan.
Clan members are asked to be active, either in-game or on the forums. Those who result MIA for a long time will be removed, but they'll be welcome to re-join the SDXF anytime.

Although the SDXF is intended to be a clan for Team Fortress 2, it's possible to form a division for an other game, as long as two conditions are met:
1) there's a large enough number of people willing to be part of the division;
2) There's someone trustworthy willing to take the role of leader for the division.
The division leader will be responsible of keeping it toghether and making sure the good behaviour of its members. If a division turns inactive, it will be disbanded.

Finally, given their permisison, established members of the clan will make a cameo appearance in the comic whenever the authors will see it fit.