1) MSPA stories exist in the format of "mock games", specifically text-based adventure games. You advance through the pages of the story by clicking links which sound like commands you would type in a text prompt to get a character to do something. Generally, the character will respond to that command on the following page.
2) MSPA stories are largely "reader-driven", in the sense that most of the text commands were supplied by readers through a suggestion box. I would select a command from the list, and then illustrate the result of the command.
Taken from the "New Reader?" section of the site