The number of levels in the game (as revealed via Achievement listings) has no particular bearing on the length of the Campaign – and our levels are split thematically and for reasons of fiction as much as they are by location or “map.” There are a couple of instances in the game where a “level” actually comprises different environments and radically different play styles that might otherwise have been split into different levels. In terms of length of Campaign, it’s similar to most other Halo games and the number of hours to complete will depend on difficulty level, number of players and play style, just like before. Some folks will rock as many vehicles as they can and try to blast through as fast as they can, while others will stare at every rock, blade of grass or hidden corner and take weeks to get through a level.
And Halo 4 - in a doubling down of the grand tradition of previous Halo games, encourages exploration, experimentation and replay with all sorts of methods, from hidden story content, to achievements, to easter eggs and beyond.
Over and above that, every copy of Halo 4 includes access to Spartan Ops, with ten weeks of content, and five missions for each of those weeks means that in terms of story-driven gameplay experience, this has far more single player and cooperative content than any other Halo game, period.