A competition.
Controversy; debate.
Struggle for superiority; combat.
To strive earnestly to hold or maintain; to struggle to defend.
To call into question; to oppose.
To make a subject of litigation; to defend, as a suit; to dispute or resist, as a claim, by course of law.
To contend.
Deathmatch, sometimes specifically one in which every player is pitted against all the others.
Chaos; a chaotic situation lacking rules or control.
Open to anyone and with no or few rules.