According to blogger Rebs Gaming, developers reconsidered their attitude towards the universe's books after player reactions to Halo: Campaign Evolved. Fans asked for events from the novel Halo: The Flood to be included in the game, but management believed that most of the audience was not interested in the series' literature.
Ultimately, Halo Studios explored the possibility of releasing an expansion based on Halo: First Strike, a story set between the events of the first Halo and Halo 2. The campaign was supposed to tell the story of Master Chief's fight against the Covenant and conclude with his return to Earth. Some missions could have been 2-3 times longer than usual.
Developers also discussed a standalone release. An inexpensive expansion would seem more logical in the absence of multiplayer and 'Firefight' mode. If the project proved successful, the studio could take on adaptations of other Halo novels. The game was not officially announced, and the information is based on data from Rebs Gaming's sources.