[Judge_S]

One setting, as is used in many other games, would be to have multiple instances of the same server, but with different rules.
One could be a PK server, where above level 5 or something, you could be PKed (in short, no peaceful mode options).
Another could be your basic server where anyone is welcome, and some basic rules are set out.
The last could be a roleplay server, and stictly roleplay. If you do not follow the rules of the server, you could be suspended from play for a day or two on the first offense. The second offense for a week or more. And the last offense, permanently.