Melee is a type of combat, where there are usually several people to a side, each side has their own objective, usually to beat the opposing side.
In this form of combat it is normal that a person may not kill from behind. However they may inform a person that they have been engaged from behind and that combatant should turn to meet that challenge. Melees generally do not allow the use of missile weapons, though there are some cases such as village football where this is allowed. Special scenarios are occasionally used, like ransom melees.