Duels

Authorized Player vs Player fights, that can take place even in safe areas.

Procedure
To make a duel a player must send a request to another, the second player must accept and may decide then which type of duel it will be.

After the duel concluded, window that indicate winner'll appear in the middle of the duel participants. Or, if both sides are ten meters apart when the victor's decided, there'll be two windows appearing at the closest point to them.

Notable Duels

 * Kirito vs Asuna
 * Kirito vs Kuradeel
 * Kirito vs Heathcliff
 * Kirito vs Heathcliff Rematch
 * Kirito vs Eugene
 * Kirito vs Lyfa
 * Kirito vs Oberon
 * Asuna vs Yuuki

Types of Duel
The types of duel are:
 * Normal Mode: Rarely used in SAO, since it will only stop when a player's HP reaches 0, and that will mean permanent death for the loser. This is the one used for Sleep PK.
 * First Strike Mode: This is the most common, the winner is decided by whoever lands the first clean hit or whittle the opponent's HP to half.
 * Time-Limit Mode: The winner is determined by whoever has the most HP within the designated time-limit. (unconfirmed)