On paper, Modern Warfare 2's storyline isn't exactly complicated. It's less The Brothers Karamazov, and more a particularly stupid episode of 24. But still - due to the clipped, rapid-fire pace of the cut scenes, and some assumptive leaps between missions - the plot can be hard to follow. The relatively authentic military speak (Oscar Mike is code for 'On the Move' BTW) is also hard to follow. So here are some answers to questions you might have been asking yourself as you played the game, and some bonus details and theories for committed-fans. Hopefully when you've read it, the events of Modern Warfare 2 will be a lot clearer. We are Oscar Mike.
What's an ACS Module
ACS stands for Attack Characterisation System. It's a surveillance device that calculates the risk of one country attacking another.
In Modern Warfare 2, one belonging to the Americans 'goes missing' and is located in a Russian airbase. Captain 'Soap' MacTavish and Gary 'Roach' Sanderson are sent to recover the lost unit in 'Cliffhanger', but the mission is compromised and the pair are forced to flee with the unit under heavy attack - but it turns out the Russians had already cracked it.
This means that the Russian invasion of America - sparked by the events of 'No Russian' - goes almost undetected, and paratroopers are able to evade local radar and land inside Washington, seizing control of the capital.
Is Ghost Gaz from Call of Duty 4?
Gaz, voiced by British actor Craig Fairbrass, was an SAS Special Forces operator who worked with Captain John Price and 'Soap' MacTavish during the events of COD4.
At the end of the game Gaz is seemingly executed by a Desert Eagle pistol, fired by one of Imran Zakhaev's bodyguards. In Modern Warfare 2, Sergeant 'Ghost' Riley - whose face is always obscured by a balaclava with a skull print - is also voiced by Fairbrass, with the same distinct London accent. Could it be that Gaz survived COD4 and now obscures his scarred face with the mask? Gaz's surname was never revealed in COD4, so it could be Riley, and it seems odd that Infinity Ward would hire the same voice actor to play two different characters. Especially one as vocal, and memorable, as Gaz.
Ghost's backstory is apparently being revealed in a series of spin-off comic books (and, if rumours are to be believed, his own separate game), so we'll find out the truth then. But as it stands, all evidence points to the two characters being the same person. On a more obvious tip, he's called *Ghost*, and the character represents a common thread between the games; a mentor to your rookie, not a detached, more omnipotent, physical constant like Captain Price.
Why is the airport in 'No Russian' called 'Zakhaev International'? Wasn't he the villain in COD4?
Yes, despite Price and his squad's best efforts in COD4, the Ultranationalists - revolutionaries who want to take Russia back to the days of the Soviet Union - managed to seize control of the country and defeat the Loyalists (as outlined in MW2's opening movie with a Lenin-style statue of Zakhaev).
Vladimir Makarov, the series' newest villain, used Zakhaev's death as propaganda to win over the populace, proclaiming him a martyr for 'Mother Russia'. So that's why the airport is named after him, and why Russia were so willing to invade America after identifying CIA operative Joseph Allen's body. Imagine if something like the airport massacre had happened during the Cold War in the '80s, and you'll have some idea why the world is in such a knife-edge political state in Modern Warfare 2.