This is kind of hard to explain, but I'll attempt to.
Let's say we have a game called General Ultimization Game. I start it, and choose to ultimize Superman. It's up to the players whether their entry is completely stand-alone, or whether it fits into their own little "Ultimate Universe" - which could be expanded on by each entry. For example, the next week could be Batman, and one player might just do him as a stand-alone entry, while another might add to his "Ultimate Universe" by building up a continuity between his Superman and Batman entries.
And then, of course, it would be up to the player whether they want to tie in other concepts, such as Doctor Who or James Bond into their "Ultimate Universe".
It's a bit confusing, but I guess we'd have to try it out before we know if it works or not.