According to the web site Massively, on October 21 at 2PM Pacific Time, the two companies will have a big reveal of whatever game they've been hard at work completing for the past year.

Joystiq opined Tuesday that the game is all but confirmed to be an MMO based on Knights of the Old Republic; while Massively, who obtained the exclusive invite for the event, predicted the title of the game could very well be Star Wars: The Old Republic.

The image above is a scan of the invitation, and the image below is the back of the invite, with specific info about location and other details blocked out by Massively.