In order to make the game enjoyable for busy types, what about starting players off with the best possible equipment? Like, let's say there was a 'beginners' mode where strafe-jumping was disabled, and the only weapons were the machine-gun and shotgun. When a new player joins the game, they start with 200/200, both weapons, and max-ammo. They also start with quad damage. So instead of having to begin with nothing and compete against players who have everything, they start with everything against players who have probably been depleted. It would give them a taste of blood, which, if they are sharks, is all they need to keep coming back. And as a disincentive to quit and rejoin the server just to get all the beginning stuff back, the system could make it so players cannot rejoin the server within five minutes of leaving.

I suppose the mode would have to be something like FFA, and it may require a kind of setup where the game never ends. Like, it only changes maps every 24 hours, and there is no frag-limit. So basically, people just come and go as they please, and when they show up, they are sort of rewarded with a bunch of easy kills.

You could also periodically grant additional quad-damages... every five minutes or so.

Obviously, there would be no real winning or losing, there would just be tons and tons of fragging.