Soon though you reach the Russian trucks and new ground, racing down an embankment and into an exposed London Underground tunnel just as a Tube train gets moving. With no time to lose (when is there ever?), you and your squaddies mount a pair of nearby pickup trucks and give chase into the tunnels. You dodge oncoming trains and fire at soldiers leaning out of the Tube carriages, and at one point you race through a station past hordes of screaming commuters.
The radio chatter becomes urgent now and your squad mates in the other pickup reach the front of the train. They target the driver, but in the confusion something happens and they swerve into the leading carriage and explode, derailing the train, which flips onto its side and continues inexorably onwards, snapping tunnel supports like matchsticks as it gradually decelerates. The rest of the carriages twist and tumble in its wake as you fight to get clear, and then we fade to black.
With just a few more seconds to compose ourselves, we're ushered into a room next door where we're invited to go hands-on with Spec Ops Survival Mode. Presented in addition to the co-operative story missions (the likes of which made up Spec Ops in MW2) and of course competitive multiplayer, which we're not seeing at all just yet, Survival is a wave-based arena mode where you and a friend fend off waves of soldiers, dogs, choppers and whatever else the game can muster.
Beginning with a pistol, you mow down each wave and accumulate currency for kills, which can be invested in weapons, tools like sentry guns and outside support like riot-shield toting NPC team-mates and predator missile strikes, all of which can be upgraded with additional funds. The level we sample is a rundown military base with a warehouse, bunker, radio dome and the obligatory shipping containers, organised into several discrete combat areas linked by handy choke points.
It looks like wave design follows set patterns, but it keeps you on your toes nonetheless, with your adversaries not averse to strapping explosive charges to their dogs or throwing in a juggernaut - a heavily armoured brute with significant firepower to complement the efforts of the lower ranks.
Like Modern Warfare 2 and Black Ops before it, then, Modern Warfare 3 proposes not just to keep you busy with depth but also breadth - and we haven't yet heard properly about competitive multiplayer either. Treyarch's Black Ops introduced Wager Matches and other minor innovations, and while Infinity Ward and its new buddies at Sledgehammer undoubtedly could just reheat MW2 for online play, they are likely to want to recapture our imaginations by getting one over their Activision stable-mates where they can.
We still wouldn't expect dramatic overhauls, but then that's not Infinity Ward's style. Call of Duty didn't start with a nuke - it's always been about measured escalation. Measured to surprise, measured to provoke and measured to make you the centre of all that glorious attention to detail. Modern Warfare 3 should be no exception, for better or worse.