10 Most Iconic Moments From Call Of Duty 4: Modern Warfare

The training in Herefordshire has all the hallmarks of SAS mission preparation as reported by former soldiers in documentaries and non-fiction titles by the likes of Andy Macnab and Chris Ryan.

You are drilled precisely about what to do in each room of the mockup ship you're to infiltrate. You are encouraged to kill with ruthless efficiency and you are given a suggested difficulty level as a result. You're even given the chance to run it again and again - drilling skills as proper SAS soldiers would.

One of the cleverest design decisions with Modern Warfare was that each tutorial or cutscene showed the player what they'd be doing sooner or later in-game.

Flashbangs, switching to a secondary weapon or knife, sprinting to a location and handling a silenced MP5 were all crucial player skills, and it meant that Crew Expendable then became a more rewarding moment for players. Without such a slick tutorial it would have been a slow level interrupted with instructions or, worse, a frustrating level the player had to replay again and again, sucking out all the enjoyment.