The most unusual vaporware title for the Com has to be the mysterious "Wyvern" game. Never actually announced as a forthcoming Com title, some of the game's images were discovered hiding in one of the game.com commercials (which are available on the Web Link CD, as well as being mirrored over in Archives:game.com). These images have been extracted from the commercials and presented here for your viewing.
The top image is a still of a short animation sequence in the commercial, showing what I deemed to be a Wyvern (a dragon-like creature) with some RPG elements. Click on the image to view the animation itself. The bottom image is another capture from the commercial, showing what is believed to be the title screen of the game. While the image is small and grainy, general opinion is that the name listed is "The Legend of the Lost Creator".
The animation sequence displays several RPG-type elements, which points towards an RPG genre.