I'm surprised at how quick this has dipped below the twenty pound barrier considering it's such a first-party hit. Not that we're complaining as it's about time the stragglers caught up to the rest of the world and checked out 343 Industries' fantastic first Halo game proper. Season 1 of the free Spartan Ops co-op DLC has just finished, but it's still available to download and is well worth ckecking out. It's still a regular on the Dealspwn post-work sessions.
Thanks to capelli at HotUkDeals.