Project Horseshoe 2018 report section 8
Introduction Many of the problems associated with making an MMO, a Massively Multiplayer Online game, come in large part from the very first term: Massively. An MMO is notably tricky to build due to technical issues involving server scaling, as well as design issues involving scaling economics, politics, level design, pacing, persistence, and progression. A rule of thumb is that development costs grow exponentially as the number of players increases, but for many years, theres been an unq...
Source: projecthorseshoe.com