RPG means Role-Playing Game. Now, I know there are more than one /kind/ of RPG, but the one that this webring deals with are videogame RPGS; for example, the Final Fantasy series, Xenogears, Suikoden, and the like. To a lesser extent sites on other not-so-RPG videogames such as Soul Calibur are allowed.
This means that sites for real role-playing games like Vampire: The Masquerade do not qualify, nor do online role-playing games in which people take existent characters and act them out.