343 Industries has remained coy over how long its cooperative, episodic campaign for Halo 4 - Spartan Ops - would run. Creative Director on Halo 4, Josh Holmes, said during the E3 2012 Giant Bombcast that it would be the size of a full campaign, but an ExpertZone survey has pinned that figure down: 12 hours, across 10 weeks of 50 episodes.

ExpertZone is a service for training GameStop employees. The slides revealed that 10 new weapons will be in the game, along with 2 new vehicles, and a new enemy class: the Prometheans, a Forerunner A.I. Halo 4 takes place on a Forerunner world called Requiem.

The information, courtesy of Little English Halo Blog, a fansite devoted to collecting information everything Halo, also showed tidbits that were dropped on matchmaking: drop-in and drop-out is available for matchmaking, allowing players to join games mid-session, along with the ability to create groups. Halo 2 supported clans - 100 players in one "group." The feature has been long requested since being removed in Halo 3.

It was confirmed there will be 10 new multiplayer maps, and new maps will come with "future DLC." The Limited Edition of Halo 4 - the only other edition available aside from the standard game, for $99 - offers a pass to all DLC.

On Spartan Ops, 5 episodes will arrive "each week" - it wasn't said whether the episodes release on the Monday of the week, or Monday-Friday, and there are 10 weeks in the first season. Missions are preceded by a short cinematic - Holmes said episodes are between 10 and 15 minutes, so between 50 and 75 minutes a week - which was confirmed to be "100% free." In total, players will play 12 hours of content.

12 hours of content is 720 minutes, so dividing 720 by 50 episodes gets an average of 14.4 minutes per episode. "It's like getting two campaigns in one game!" the survey said.

It's not known whether some elements from the main campaign will be used, but Frank O'Connor - franchise development director at 343 Industries - said during the same Bombcast that there would be new environments. In Halo: Reach and ODST, elements from the campaign were reused (especially in Reach - all the environments were reused that were available from launch).

Halo 4 releases November 6 on Xbox 360.