Alex Garland was paid $1 million by Microsoft to write an adaptation of the popular game. Microsoft then sold the script to Universal for $10 million.
When Guillermo del Toro left the running, Peter Jackson settled on the novice Neill Blomkamp for director. Blomkamp worked to exhaustion for five months preparing the project, which went as far as constructing props and costumes and producing short Halo-themed films as test footage. The project then collapsed. Jackson allowed Blomkamp a free reign in choosing a new project, which led to District 9 (2009). Although Blomkamp is still "creatively interested" in Halo, he does not wish to return to the project after working on it for so long and watching it collapse.
Producer Peter Jackson asked Guillermo del Toro to helm the movie, but del Toro turned the offer down so he could direct Hellboy II: The Golden Army (2008).
A rumor was started that Alex Garland's script had been dropped, and that D.B. Weiss had replaced him as the screenwriter, but Weiss confirmed in an interview on Gamesetwatch.com that he was only revising Garland's script.