Free-For-All (often abbreviated as FFA) is one of the battle gamemodes in SuperTuxKart. It's playable in online and offline games.
In FFA players have to try to hit others with powerups as many times as possible while not driving into bananas or any other "bad", rescueing things like e.g. water or lava, and not hitting themselves. Each hit gives 1 more point for this player, each bad action gives -1 point. The goal is getting as many points as possible, or being the fastest player to reach the maximal possible number of points.
Typically a game is played until 6 minutes pass or a player scores 20 points, and several players are required to play a game because obviously a lonely player cannot get positive points.
You can find a list of FFA arenas here.