I still want a movie of Halo.
The way to do it is as a trilogy covering the history of the Covenant, opening with the war between all the alien species pre-Covenant (i.e. no Marines at that point), then the Prophets unification of them all as they seek the Forerunner rings. The rest of the first movie documents how an Elite rises through the ranks, eventually being promoted to Gold Elite as a reward for his courage and leadership in the Fall of Reach. So, we see the Humans through Covenant eyes, giving a supplementary dimension to the game's story-line (which is pointless to recapitulate).
The second film follows this alien anti-hero through his character arc, showing how he becomes the Arbiter. (i.e. parts of Halo 2)
The final film has him paired with Master Chief. This allows you to have extended sequences of action where Master Chief is characteristically silent that work dramatically, because the Arbiter is speaking... moving the plot along, providing necessary exposition. This culminates in his assassination of the Prophet.
- this is only a rough sketch as I haven't read any of the books. The main point I'm trying to demonstrate is that a Halo trilogy could be made if done from a fresh dramatic perspective. Also, it is necessary to think big (3 films) as all the costs of props, etc could be spread over all the live-action movies and Peter Jackson could film the principle photography in one go in New Zealand (e.g. Halo-ish landscapes) for a whole year, with Neill Blomkamp involved in pre/post production and handling the 2nd unit, technical stuff. This is because it would be easier to get the money for a Sci-Fi "Lord of the Rings" with Peter Jackson directing it.