Killing someone within the same karmic influence will yield minimum gains.
And maximum losses I would hope. Blue on Blue crimes should result in a large karma loss or someone being Blue/Red/Grey/Purple wouldn't make a difference in them posing a threat. In fact, the smart PVPers and clever griefers would just grind their blue points up on red guys then PK other bluebies who trusted them to be saints. As long as you have enough karma points to spend on the murder, you can continue masquerading as a sheep when you're truly a wolf.
Regarding all the complaints about the flaws of the system, what about the ability for PLAYERS to decide whether to punish someone for killing them? If you decide to punish, the penalty is severe, and typically reserved for jerkwads. But if a townie accidentally murders you or you're just out PVPing random people who also like to PVP, they can choose not to punish you and the penalty would be minor. Essentially there should be two different penalties... a light offense automatic penalty, and a heavier offense punishment penalty.
Perhaps implementing PVP flags can also help alleviate issues. If you want to PVP with NO karma penalties, you enable your PVP to ON and are then free to kill players who are also enabled as PVP ON. But if you kill someone who is PVP OFF, you still suffer the karma penalties because that individual did not want to PVP. In this way, people who simply enjoy mass murder can run amok killing like-minded mass murderers and not have to worry about the karma penalties involved. They would still get the occasional penalty for blue kills, but it would be much less severe over time, especially with karma decay resetting them closer to grey.
Finally, to encourage PVP in its finest, balance must be achieved between good and evil. Since Evil currently gets all the free loot from murdering blue players (and let's face it, an evil player rarely carries any loot), perhaps setting automatic bounties onto them would be beneficial. It would be in a Good player's best interest to seek out and hunt down Evil players, fostering PVP between the two factions. The Evil players are thus rewarded by illegitimate gains from neutral players while the Good players are rewarded for keeping the server safe from them and retribution for their crimes. Hunting down evil players for a righteous reward sounds very much like what a good player does, but it would also make evil more wary of them. Thus both sides would get the same penalties for being too evil or too good. The good players have monetary rewards while the evil players have item rewards, and both are encouraged to kill each other.
It's the concept of PK and anti-PK that I found most engaging about the Rallos Zek server in EQ.
So those are my thoughts on the system.
- Punish/NoPunish karma variation for kills
- PVP flagging for the gungho Hero enthusiasts
- Bounties for Evil to breed Good/Evil wars