PKOK

From Wormhole Sci-Fi MUD Homepage

The wormhole is not a player-killing MUD, although some individuals choose to fight a duel or even a protracted vendetta. If you want to fight in this way, in any area of the game, toggle PKOK to 'on'.

There are a few PKOK (Player Kill OK) areas on the Wormhole. These are lawless places where the normal rules do not apply. Anybody can attack or be attacked in a PKOK area. Avoid such places if this concept worries you (and keep your 'summon' permission toggled off). Murdering players who don't want to risk PKOK is an offence, and could result in jail time.

Examples of PKOK zones include Warzone, and Paradoxian Plumbing

If you want a 'cute' version of combat without the messy corpses, lost equipment and such, consider arranging to meet in an arena, or starting a war.