Call of Duty: Black Ops

"So," says the silver-haired man with the steely blue eyes, "What's your favourite videogame?"

"Tomb Raider," I say. The man nods and looks back at me as if expecting a longer answer. Maybe it's his steely blue gaze, maybe it's the commanding tone of his voice, maybe it's the fact it says "MILITARY ADVISOR" on his polo shirt, but I feel like I have to keep talking.

"Um, and FarmVille. I like FarmVille," I babble.

"I've seen that on Facebook," says the man. "People always offering me baby pink cows."

"You don't play FarmVille, then?" I reply, as a voice in my head says, 'This man was in the US army. He has killed people. And you are asking him about FarmVille.'

"I don't play anything except Call of Duty," says the man. "Not enough time. Wood to chop. Rocks to split."

And military advice to give, of course. The man I'm failing to make decent small talk with while I wait for the Gamescom Call of Duty: Black Ops presentation to start is just one of many advisors working on the game. As community manager Josh Olin explains, they have some astonishing stories to tell.

"These guys have got balls of steel," says Olin. Not just eyes, then. "When you see those stock black-and-white photos of North Vietnamese army patrols - they weren't set up, somebody actually took those photos. They went behind enemy lines and they weren't holding a gun, they were holding a camera.

"Of course, they were doing more than just surveillance," Olin continues. "They were also blowing sh** up."

It's this aspect of the job which Treyarch appears to be focusing on with COD: Black Ops. Explosions seem to occur about 48 times per second in the two levels we're being shown today. At no point does anyone attempt to take any snaps. Disappointing for those hoping this instalment in the COD series might feature some Afrika-style photography missions, then.

Instead we find ourselves in Vietnam, in 1968, in the back of a helicopter which has just crash-landed in the middle of a murky lake. The first pilot didn't survive the crash. The second pilot is alive, but only long enough for him to turn round and get shot in the face. Coming under heavy fire, the helicopter sinks below the surface of the water. We watch as the playable character jimmies the latch on the door and swims away to safety.

Except, as this a Call of Duty game, he actually swims over to an enemy boat, pulls himself over the side and despatches the occupant with a swift knife to the throat. A VC on the banks of the lake is firing furiously at our hero, who unleashes a single round from his pistol. Everything slows down for a few seconds as the camera zooms in on the bullet and follows its trajectory through the air, across the lake and straight between the enemy's eyes.

This, Olin explains, is a scripted sequence; you can't just jump into a bit of bullet time whenever you feel like it. "We wanted each level to have cinematic moments people would remember," he says. "The Call of Duty titles are scripted games where you follow specific paths, and we don't want to mess with that formula."

This particular path now leads us into the jungle, where we're rejoined by some other members of our troop. We're heading towards an enemy village. The inhabitants are oblivious to the carnage which has just occurred down by the lake, judging by the way they're just hanging about in hammocks.