Microsoft today announced that the Xbox 360 exclusive game “Halo 3″ has officially become the biggest entertainment launch in history, garnering an estimated $170 million in sales in the United States alone in the first 24 hours. The Xbox 360 title beat previous records set by blockbuster theatrical releases like “Spider-man 3” and novels such as “Harry Potter and the Deathly Hallows.” “Halo 3″ is the conclusion to the epic trilogy and picks up where “Halo 2″ left off, answering questions around the fates of the beloved protagonist Master Chief and his artificial intelligence sidekick Cortana as they struggle to save humankind from destruction at the hands of the alien…