Face-Off is the first multiplayer game mode to be featured in the Guitar Hero series starting with the first Guitar Hero game, which was the only multiplayer game mode in that specific game.
In Face-Off, players take turns playing sections of a song or occasionally playing at the same time in a call-and-response-style game. Both players can select their own difficulty level and will not fail the song if multiple notes are missed. The objective of Face-Off is to have a higher score than your opponent by the end of the song.
Face-Off has appeared in every main iteration of the Guitar Hero series up until Guitar Hero: Warriors of Rock. For the multiplayer game mode where all players play the entire song together, aiming for the highest score, see Pro Face-Off.