Call of Duty: Black Ops Preview

"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.

Treyarch's not talking about the multiplayer aspect of the game yet, but expect more news soon.

"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.

Weapons include the always popular AK 47, among others.

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.

But it's not long before their peace is interrupted by a bit more neck-knifing and some strategically lobbed semtex. As the alarm is raised the scene quickly turns to chaos - the air is thick with bullets, wooden huts explode at a rapid rate and the chickens go mental. Women and children are curiously absent from the scene but there are plenty of grown men to shoot. Our hero takes advantage, blasting away until they've all stopped moving.

Time to move into the tunnels running out of the village and into the jungle. A bloke called Reznov chucks us a torch and we wish he hadn't, seeing as all it just makes it easier to see the scurrying rats, crawling cockroaches and bits of leg lying about the place.

A tense scene follows. A soldier drops suddenly from the roof of the tunnel and our hero instinctively fires, only to realise he's actually a bloke called Swift who is on our side. But there's no time to apologise. Before Swift even has time to tell us to keep our sh** together, an enemy appears and stabs him in the face.

Pressing on, we catch up with another team-mate, Reznov. "Where is our friend Swift?" he asks.

"Dead," our hero replies.

"Everybody dies, Mason," says Reznov profoundly. "Your turn, my friend. I will follow."

But before we get the chance to see how Mason fairs when leading the way through the tunnel, and whether he learned his lesson regarding the whole Swift incident, it's time to look at the second level on show today. Titled Payback, it's a set piece which involves flying over a Vietnamese valley in a helicopter, dealing death and destruction to the enemy below.

And to think there seemed be a lot of explosions in the other level. It's non-stop here - bases, ships, tanks, tents, telecomms towers, rope bridges, munitions dumps and endless rows of palm trees burst into flame all over the shop. This goes on for several minutes without any kind of retaliatory interruption, suggesting the title of this level has as much to do with rewarding the player with a bit of carefree carnage as it has to do with the plot of the game.

The plot isn't something Treyarch's revealing a great deal about today. Olin does promise us a "deep, complex narrative", but also one that "follows the fine line between complex and confusing". He goes on to admit that "creative liberties" have been taken with regard to the timeline - that helicopter we just saw, for example, didn't actually exist in 1968. "Fun is the most important thing to us; authenticity is second," Olin confirms.

Besides, he says, the truth is often stranger than fiction. "The military advisors we've been talking to did the most crazy, incredible things. People look at some of the sequences in the game and say, 'That's over the top, that's not realistic.'

"But some of the things these guys were telling us were so over the top we said, 'We can't put that in the game. No one would believe it.'"

With that the presentation's over. When I head back out into the booth there's no sign of the military advisor I was chatting to earlier, so I can't ask him about any of the crazy, incredible things he did. He's probably off chopping that wood, splitting those rocks and practicing his steely gaze. Or, you know, blowing sh** up.