I got an update from Elbert Perez at Occasional Gamer announcing his new Xbox Live Indie Game Scribble Defense. Scribble Defense is mish-mash of different Tower Defense Game concepts. Players move around as avatars, money is not automatically deposited, it has to be picked up, towers are effectively "upgraded" if the player is within their attack distance, as well as movable waypoints. Enemies can change their heading if target waypoints are influenced by the player or randomly moved. It will have two player co-op support and you get a feel for how it plays from this trailer.