When did halo 5 begin development?

Just a curious question.

J2015-10-05T09:08:18Z

They don't release exact dates, but a good estimate is that the story boarding began not too long before Halo 4 released, so probably early to mid 2012. In terms of actual development of the game, probably after Halo 4 so early to mid 2013

Anonymous2015-10-05T09:51:05Z

Probably around the time that the Xbox One was revealed.