Refereeing for Massively Multiplayer Online Games (MMOGs) currently relies on centralized architectures, which facilitates cheat prevention but also prohibits MMOGs from scaling properly. Centralization limits the size of the virtual world as well as the number of players that evolve in it. The present paper shows that it is possible to design a peer to peer refereeing system that remains highly efficient, even on a large scale, both in terms of performance and in terms of cheat prevention. Simulations show that such a system scales easily to more than 30,000 nodes while leaving less than 0.013% occurrences of cheating undetected on a mean total of 24,819,649 refereeing queries.