 Alternate reality games were used to promote the release of the games in the main trilogy. The Cortana Letters, a series of cryptic email messages, were circulated by Bungie prior to Halo: Combat Evolved's release. I Love Bees was used to promote the release of Halo 2. The game revolved around a website created by 42 Entertainment, commissioned by Microsoft and endorsed by Bungie. Over the course of the game, audio clips were released that eventually formed a complete five-hour story set on Earth between Halo and Halo 2. Similarly, Iris was used as a viral marketing campaign for the release of Halo 3. It featured five web servers containing various media files related to the Halo universe.
