Actually, i think there have been talks about it, but dont think anything has materialized yet. You could not make a good, live action halo movie for under 100 million dollars due to all the special effects (and in reality, prob more like 150). Of course in reality, you could make any movie w a hand held and a bunch of friends for very little.
You are not able to make a Halo movie w/o the permission of the company that owns the rights, in this case Microsoft. You wouldnt be able to use the name, or anything resembling the likeness of the characters, etc...without paying them for the rights first.
As big of a company as Microsoft is, they would never let anything be made that could potentially damage the image of their most successful video game franchise, thus, getting the rights would be reserved to major movie studios.
Your best bet would be to take the halo story and characters, and then change them enough so as they dont resemble Halo too much. Good luck!
