The basic form of each forum game allows players to essentially play "god" over a particular nation, planet, or other political grouping depending on the game. Destiny of the World, one of the most basic of the forum games, has one player control one nation and interact with other player-controlled nations to achieve a number of self-set goals.
The two basic posts in each forum game are the newspost and the event post. The newspost is how each player updates the nation or planet he or she controls, though some are used purely for flavor and broader interest. They vary in length from a paragraph to several pages, with the latter preferred for quality's sake. Event posts are similar to newsposts in every respect except they are posted by a forum game moderator to act as an outside influence on a player nation, usually for bad -- like natural disasters or political crises -- though sometimes for good. The general format is meant to be like that of a newspaper or news magazine.
Games playable in this manner include The Frontier and Diplomacy.