Can halo be built in real life?

If by real you mean come out. NO

But Bunnie (Halo's Creator) has said the rumors about a halo related project were true. Sadly the announcement has been cancelled from E3 (Blame Microsoft will be announced, just wait.

Do some research on google for more info.

YES HALO 4 IS COMMING OUT. The reason for the roamers is because 343 industries had no idea what the story line should be they basically had no idea what they where doing.