It started with a nuke.
Except, if you ask me, that's a popular misconception. The nuclear weapon that goes off in Call of Duty 4: Modern Warfare may have been the smoking gun that drove us toward things like Modern Warfare 2's infamous terrorist siege in a Russian airport, but the shock and awe at the heart of Infinity Ward's single-player campaigns began longer ago than that. Perhaps it was in September 1942, during Call of Duty 2's Russian campaign, when your commander told you there weren't enough weapons to go around and you should wait for the man next to you to die, then use his.
So it shouldn't be surprising that while other action threequels struggle to manage expectations set by simply Making Everything Bigger last time around, Modern Warfare 3's campaign still knows how to make an impact.
Images of smoking skyscrapers in Manhattan and London Underground carriages burning in the dark may be blunt instruments in some respects ("respect" not being a word I expected to feature in this paragraph, for what it's worth), but plunged into their proper context they provoke a variety of responses. A giant worm, meanwhile, provokes just one: "A giant worm!" And where do you go from there?
The Call of Duty formula certainly works, then - probably not the big most exciting revelation on this page - but for the likes of Sgt "Frost" Westbrook, part of a Seal team swimming around somewhere in the waters off Manhattan island, there's no time to ponder the humanity of it all, because there's Ruskies to kill.
The first of two single-player levels that Infinity Ward has shown to date (along with Spec Ops Survival Mode, of which more later) was featured at Microsoft's E3 conference but deserves a recap.
You start off underwater, blowtorching through a metal grill in the gloom, listening to the sound of your rebreather and a few quiet instructions from your squad leader as the crosshatching melts away. Kicking free the loosened mesh, you emerge into a large space packed with what look like trucks, cars, buses, and New York's iconic yellow cabs. You're in the flooded Brooklyn tunnel.
You can see why it's flooded up ahead - the reinforced concrete wall has been wrenched completely open, presumably by an explosion, exposing the occupants to millions of tons of Upper Bay. Outside it's murky but beautiful, the riverbed clogged with a mixture of industrial drudgery, piping and broken military hardware. As you power your little one-man sub through the gloom and wait for motion on your sonar, you see a vast ship - you don't know whose - torpedoed and sinking into the depths ahead of you.
You swim under it and then more torpedoes glide overhead and your sonar starts to resonate, before the Russian submarine you've been sent to infiltrate fills your view. Your squad leader instructs you to hold position while it passes, which takes several long seconds - we're not used to stopping in Call of Duty - and then you advance and plant an explosive charge on its rudder. The force of the explosion cripples the sub and it has to surface, so you do likewise.