Very tricky to accomplish as long as people can interact with each other in the real world and bypass whatever rules and restrictions you have in the game rules, be it in terms of just communicating in situations where they shouldn't be able to or running multiple accounts and characters at the same time to boost their power and influence.

You'd need to get extremely draconian with the anti-cheat, require real world ID for account creation, not allow new player once the game started and all that.