I dunno, IMO, the first three rules of good game design are:
1. Never punish a player for actions beneficial to the game (not the same thing as 'actions that would be 'beneficial' to other
people...').
  We WANT them doing certain actions, including being 'thief-like'
2. Never give other players the power to punish a player.
  This will lead to abuse. Punishment should only ever be meted out by someone who is answerable to some form of authority
outside of the game.
3. Never punish a player for actions outside his control.
  A player cannot control the actions of another player, never EVER cause one player loss through the actions of another. This is a corollary to rule number 2. It's open to abuse.
Let's look at PvP Theft, PvP-T for short. There are a couple of fairly major differences between players and mobs. First and foremost is that players represent, in game terms, a time consolidated, upwardly racheting gear system. What do I mean by that? It means that players, as holders of gear are MUCH more valuable than mobs are when someone is out looking for gear. Because the gear a player has can be seen as a direct representation of the time spent aquiring it. Mobs on the other hand, are not nearly so rich a resource for aquiring gear. The result of this gear availability imbalance is very likely to be smart players stealing gear off of other players because
a) one always knows where to find players, just hang around a merchant, they'll show up, and
b) players have great gear, mobs MAY have great gear.
So, what have we established? That given the opportunity, the smart player will try and aquire his gear from other players, not other mobs. It may take a little while to find a player with gear, but consider when gear-relevant meshes are installed: Players become walking signposts of 'Come get my great stuff!'Â
That's the side of the prospective thief, and it does indeed look slick and juicy. We have enouraged PvP-T and Thieves will indeed act like thieves.
What about the side of the 'victim'? Let's give our victim a Greatsword of Ubar-Leetness. It's a quest reward from a quest chain that's no longer available (the greatsword was deemed to be too good for its level) but the two or three players who had finished the quest before this was determined were allowed to keep their prizes. This is a not-too uncommon occurance in small gaming communities - people like to be nice when given the chance. Would you allow a thief-type player to grab that? Remember, there are only two or three examples of this item in the entire game. This object is, quite literally, priceless. Do we let a prospective thief have an opportunity at aquiring such an item at another player's expense? If so, how is this different from griefing? If not, then at what level of 'rarity'
do we allow items to be stolen? A drop rate of 1 in 100? 1 in 1000? How about items that are rewards from non-repeatable quests? Are those items up for grabs too? These are just SOME of the reasons why PvP-T isn't necessarily a good idea.Â
The best reason, however is simply this: By allowing a thief to steal an item from another player, you allow communities to form witch-hunts. Someone does something that the community at large doesn't feel is acceptable, it doesn't matter WHAT that is, it could even be trivial, the fact remains that you have now allowed people to log onto their Thief type characters and steal another players gear as 'punishment'. It doesn't even matter if there are limits put in place. All sorts of limits can be placed, but they can ALL be worked around in some form or another. Just to prove a point, let me show you how:
1. A 'Thief' can only steal one item from any player within 24hrs.
  Easy, get your friends to do the same.
2. A 'Thief' can only steal one item from any player
ever.
  Then why bother allowing players to steal from one another?
3. A player can only be the 'vicitm' of a theft once per 24hrs.
  Then you do it again tomorrow, and tomorrow and tomorrow (as it creeps in this petty pace from day to day)
Other variants of the above merely slow the process down.
It isn't up to us - the community as a whole - to determine who can and cannot play a game. If you don't like someone, /ignore them, problem solved.Â
THAT's the problem with PvP-T. As long as a process is open to abuse, given enough time, it
will be abused, that's a guarrantee. Better to not allow it in the first place, when it's a game we are talking about. Games are meant to be fun, but fun is never had at another's expense.
So, what's a person who wants to play a 'thief' to do?
Well, there are several options that follow all three rules of good game design.
1. Allow would-be thieves to 'steal' money from other players. This money isn't actually taken from the accounts of the 'victim', but generated on the spot by the game, as a reward for a risky activity. Failure can mean an imposed penalty equal to some multiple of the amount stolen - enforced by the guards. To further allow for thiefly activities, if the thief can elude the guards for a period of time, they 'forget' - it's a large city, with many things going on and a pick-pocket nabbing a few (or even a lot) of tria from some overly rich adventuring type isn't really high on the priority lists of the guards. This isn't Smallville, USA where robbing a convienence store is news for the month, this is Hydlaa, where invaders from above are a very real problem.
2. Create in-game activities generally open to just thief-types (but circumventable by others with some real effort). Create mobs that carry keys that, if killed, lessen some reward that players like. A highly skilled pick-pocket can be a real asset here. Create doors that are locked, and chests that are trapped. Make them common enough that it really pays to have a rogue-ish type around, but not so common that it's ever a necessity - no type of class should ever be a necessity.Â
However, you should allow say, blacksmiths or another artisan type, to create single use skeleton keys (of varying levels for varying locks) out of expensive materials that anyone can use.
3. Allow thieves to get a 'free' draw from a mob's loot list by using the pick-pocket skill. Failure 'enrages' the mob and makes it much harder to kill, but success brings great reward. Using a three-valued logic, it's simple to create a small chance at total success (you get an item or two), a large chance of partial success (you don't get anything, but you don't anger the mob either, allowing you to kill it normally), and another small chance of total failure (you don't get anything and you got caught, good luck killing that mob!).
4. Create situations that can be 'solved' just as well by being sneaky as by being overwhelming. Don't consider it 'cheating' when a clever player uses his stealth skills to sneak past the guards and then uses he open-lock skill to unlock the 'Chest of Great Renown' from within the King's bedchamber. He's playing the game using his skills as much as someone else is using theirs.
There are plenty of ways out there to make it highly worthwhile to be a rogue-ish type. Just remember, none of the GOOD ways involve hurting another player of a
game.
