Tribes 2 did something kinda like that I think, in order to play you had to register a player name which linked up with the serial from your CD. Pretty nifty idea, except for the many people who wanted the same name and couldn't get it. Of course, they allowed you to have alias names (as many as you wanted I think) and those could be duplicates of other people's. problem was that sometimes you needed to use the primary name for stuff (some servers wouldn't even let alias names in the game to play). But I'd assume you'd never have to worry about not being able to ban someone for good
