In addition to putting the rules under a tab in the website, have them listed when someone registers an account, and have one of those checkboxes that says "I agree". You all know what I'm talking about - when you download a program or sign up for an online service you have to scroll through some "articles" (that no one reads

Specifics:
See above, please bitch about this post not following the form exactly

Why it is needed:
Right now, there's no "gravity", if you will, about registering for CC. People just go to the front page, type in a new email and a password, and create a multi. I'm not saying that this will morally guilt anyone into not making multis, but having some sort of "contract" they have to agree to will make them think twice about cheating.
Also, those people who are like "but there's secret alliances in real Risk!" won't have an excuse anymore. I'm not saying that this is a legit excuse, but this would eliminate any confusion.
Fin.