There would be at least 9 people, at least one for each of the positions on the D&D alignment scale (Chaotic-Neutral-Lawful and Evil-Neutral-Good), and the game would end when no two people left alive had alignments that directly opposed each other (i.e., either all good people or all evil people dead, and either all chaotic people or all lawful people dead).
Then I took it a bit further in my head, and was wondering what it would be like to make the different players actual PC's, with stats and saves and things... they'd get abilities based on their classes (which I would assign, of course), and, instead of targeted abilities automatically working, the targets would get to make the appropriate saves, etc.
Then I realized I should probably moderate a normal game or two first before I went trying to pull this off
