Let him be responsible for himself. He knows good and well that he needs to have the novel read by the first day of school and he's had all summer to do it. If he fails the comprehension tests and has to be embarrassingly remediated, then so be it. Let this become a learning experience that he won't forget.
You've taken away the TV and computer, why is he still playing HALO? If you want to have the bottom line, confine him to the house without privileges until the novel is finished. This includes no friends, no TV, no computer, no video games, no phone, nothing until the novel is completed. The incentive is that the sooner he finishes the novel, the sooner he gets his privileges back. But if he still refuses to read the novel, then refer back to my first paragraph and let him learn his own lesson. Depending on the length, he can have it finished in 3-4 days depending on how long he sits and reads. Ive been known to read a complete novel in 8 hours, so I know it can be done in 3-4 days, a week at the most.
If the book isnt required reading by the school, then I would tell him, OK you don't have to read this specific book, but you do need to read something outside the Sci-fi genre and on a 7th-8th grade reading level - those are the standards, and he gets to choose a novel of his own picking but YOU have to approve of it using the measuring tool I've just given you.
You're too funny!!! 