A friend of mine wanted me to discuss various features in MMORPGs (such as world PvP) and which games got them right, and which ones didn't. I think this has the potential to be a fairly lengthy topic, so I'm going to break it into several posts over the course of the week.
World Player vs Player (PvP)
Player vs player combat has become one of those "must have" features for modern MMORPGs. Many players won't even touch a game that doesn't include some sort of PvP (consensual or otherwise), and many players who aren't even remotely interested in participating in PvP still consider a game incomplete if it doesn't offer some form of it.
World PvP refers to player vs player combat that takes place in the normal game world. Any player can be wandering around and encounter PvP if they're in the wrong place a the wrong time. The PvP may only occur in certain areas of the game, but there are no artifical barriers to entry. Contrast this to instanced PvP, which are generally specialized battlegrounds of some sort where players queue up for (hopefully) evenly matched battles against appropriate opponents.
Ten years later I still think Dark Age of Camelot nailed world PvP better than any game before or after. Way back in 2001 I was fresh out of EQ and Anarchy Online, and not at all interested in PvP. I picked up Dark Age of Camelot solely because of the setting - Arthurian legend. I started out in Albion (the human/Arthurian side) but eventually switched to Hibernia (the celtic mythological side). I leveled quietly in the PvE areas, and PvP was something that happened to other people. Eventually though, I reached a level where groups were forming for PvP (or realm vs realm (RvR) as it was called in DAoC) all the time, and calls would go out for help defending such-and-such keep or "save the relic" or "help us get control of Darkness Falls" and I got drawn in. When everyone around you is racing off to defend the "honor" of your side, it's hard to sit around and keep grinding monsters. So I went out, joined groups for PvP, and was absolutely terrible at it. But it was thrilling all the same. Static monsters can't get your adrenaline pumping the way a player opponent can. One of the compelling factors was that the PvP effected everyone, even the PvE players. Gaining access to the PvE dungoeon Darkness Falls was a huge boon for PvE players, but could only be accomplished through PvP.
Over time I became merely mediocre (rather than terrible), but the main point is that I participated. The game managed to draw me in and get me to become invested in a type of gameplay I'd had no interest in. It did this by fostering an amazing community and providing goals in the world worth fighting other players over. Balance was always an issue, and I think DAoC was the originator of "flavor of the month" classes/builds, but the core PvP was fun, dynamic, and almost entirely player driven. The fact that Dark Age of Camelot consisted of three sides, Albion, Hibernia, and Midgard, provided natural population balance by allowing outnumbered sides to join up against the overpopulated side. This is a powerful population balance tool that has been missed by essentially every game since.
Which brings us to the game that touted world PvP as a feature and did (in my opinion) the worst job -- World of Warcraft. Early on there was virtually no reason to engage in world PvP. People did it just for the heck of it, but there were no goals to fight over, nothing to be acheived by beating the other side into the ground except the satisfaction of having done so. There was nothing to unify the sides over, nothing that could be lost unless players intervened. There were also only two sides, so if one side outnumbered the other (which was commonly the case) there was no recourse for the outnumbered side except to drown in the sea of enemy players. So world PvP was pointless, and indeed it pretty much vanished as soon as WoW introduced their Battlegrounds (instanced PvP), but that's another article. In Wrath of the Lich King WoW added "world PvP" through Lake Wintergrasp, which was a central location with a goal hopefully worth fighting for - a raid instance and a bonus for the side that controlled it. However, it wasn't really world PvP. It was more like instanced PvP without a queue. The objectives could only be attacked at set times, and there were player limits per side. If you showed up too late and the match was "full", then sorry, no "world" PvP for you. If you showed up before or after the match time, you were also out of luck until the next match a few hours later. I understand why the limits were put in place, but nevertheless they were so limiting as to make the area just a glorified battleground.
Why no game since Dark Age of Camelot has launched with three fully developed sides engaging in pitched PvP battles is beyond me. Even Dark Age of Camelot's spiritual successor, Warhammer Online, only had two sides, and suffered for it. Nevertheless, I think it's a key part of crafting good world PvP in a standard MMORPG environment, and I doubt any game will topple DAoC from it's throne until they take everything that was good about DAoC PvP and iterate it with modern improvements, much as WoW did to Everquest's PvE.