A group of filmmakers hopes to get to the bottom of the mystery on Saturday by digging up the concrete-covered landfill in search of up to a million discarded copies of "E.T. The Extraterrestrial" that the game's maker wanted to hide forever. The game and its contribution to the demise of Atari have been the source of fascination for video game enthusiasts for 30 years, and the search for the cartridges will be featured in an upcoming documentary about the biggest video game company of the early '80s.