I've participated in several diceless online roleplays. They really didn't need any infrastructure besides a forum which allows adult content and swearing, and a pool of interested people. Getting enough of a population base to get started is the problem. Most forums with active roleplaying subforums, such as SoFurry, GaiaOnline, and Literotica, attracted members by some other content and a certain percentage of those members discovered a common interest in roleplaying, started to roleplay, and were given a subforum after it became clear that the population was producing a sustainable amount of roleplay threads.
I ran a roleplaying board with a small team of administrators for five years. It was good fun, but after a while, story lines become recycled if you don't have a moderation team that is dedicated to throwing prompts out to people and such.
Okay I finally understand what you mean by RPG in your circumstance.
I'm not even sure this is viable to maintain as a writer -- to guide a collaborative plot line that spans an entire world or even how to really manage it. I think that is where I keep getting snagged.
You might look at it from the perspective of a team of writers as used in television shows etc. An overarching set of guidelines for development are established and then individual episodes are farmed out to individual writers (or smaller teams within the larger team) to bring out about the required guideline's immediate needs as well as create their own story within that "universe".
A more sizeable example would be Warhammer 40k Universe which contains a number of differently authored books which remain (mostly) true to existing canon as well contributing to expansion of the canon.