[Monochron]

I'll throw in my speculation as well. I'm thinking some sort of asymmetric game-type or field. One alliance is assaulting the other's Stronghold. Possibly switch mid-math ala 2005 or possibly even (though unlikely) playing a whole match on one side.

Capture the flag type game fits . . . but I'm not sure it could be done in a way that isn't just robots spinning their wheels against each other for two and a half minutes.