Complementing the campaign is a versus mode that lets you pit any of the game's playable characters together. Since the story caps the campaign at a few hours of play, versus mode is intended to extend the game's value. Head-to-head bouts don't succeed in doing this, however. Instead, it feels like tacked on and worthless. Perhaps some entertainment can be gathered from watching characters run about the same versus arenas, but it's fleeting.
The same can be said of Friend or Foe as a whole--it's a fleeting interest. While it's pleasant to look at, the basic combat system lacks variety or depth. But then again, at $20, what do you expect?