A friend and I are working on a project that pits one player against everyone else in the game. Sort of like Clue meets the Juggernaut gamemode.

One player is chosen as the "juggernaut" and is tasked with taking out all of the other players using the advantage that he is visually no different from the other players and is granted a suite of tools for taking out players silently and efficiently; Rewarding patient players for avoiding aggressive play.

It was brought up that features and scoring should be designed so the game can be played competitively if the players like, but we're not entirely sure how that would work.

Who would the juggernaut be competing against?
Would it be fair to compare the scores of two juggernauts in completely separate rounds, despite the regular players providing a different environment?
Is it even possible to have a competitive system outside of symmetrical gameplay?