Since its announcement in April, there’s been almost as much secrecy, rumour and speculation surrounding the next instalment in the Call of Duty franchise as around the real-world activities it’s fictionalising.

Was this to be Call of Duty’s long-awaited foray into the Viet-Nam war? Was it a different take on Call of Duty? With Infinity Ward in turmoil, was World at War developer Treyarch taking over the franchise? Was it treading on Infinity Ward’s toes by moving away from World War II and towards the modern era?

At a press event in London, we had our first chance to clear up some of these questions and take a good look at the game with developers on hand to walk us through some of the new features and gameplay we can expect when the game eventually hits in November.

The first thing to understand is that Black Ops isn’t focused on any particular conflict, but on the activities of US Black Ops units during the Cold War. While missions will take you to Viet-Nam in 1968, you’ll also see action in other locations at other periods, as you follow a couple of elite operatives through the deniable conflicts of the Cold War era.

“We really wanted to focus on variety” says studio head Mark Lamia. “By doing the Black Ops and doing the secret wars it’s allowed us to leverage some historical backgrounds and some backdrops you might not be aware of.”

For Treyarch, it’s a rich background for a big, heavily cinematic action game  - or "epic entertainment experience", in Treyarch parlance. The studio immersed itself in the conspiracy and paranoia of the times, consulting with veterans of the US Studies and Observations group, one of the first Black Ops units to emerge during the 1960s. The whole premise of the story is that we live in a world where everything you know is wrong.

One thing Treyarch isn’t planning to do is break the series with dramatic changes to the core gameplay though.

The two missions we saw in action left us in no doubt that Black Ops has all the hard-hitting gunplay and overblown drama you’d expect from a Call of Duty title. In fact, Lamia talks of the studio’s desire to “ratchet up the intensity” and of “raising the bar on everything we’ve done before”.

At the same time, Black Ops does bring something new to the franchise. Apparently, Treyarch wants to mix things up for the CoD veteran, throwing in elements like fully interactive rappelling and breaching plus, at specific points, direct command of other troops on the field.

In the first level we saw being played, the action began with a trip to high altitude in an SR-71 Blackbird, followed by a sequence where the player could command troops into action using surveillance and radio equipment. With one objective completed, the view then switched to one of the troops on the ground, ready to begin an assault on a soviet relay station high up in the mountains.

The new emphasis on leadership represents something of a departure. In previous Call of Duty games, the heroes have always been following objectives from one marker to the next, taking orders all the time.

Now it’s your turn to take the initiative a bit more. “These guys are leaders” says Lamia, “they’re charismatic, they’re experts, and they have something to offer.” As a reflection of this your protagonists will, for the first time, be voiced, giving instructions, providing intel and calling out threats in the environment.

What’s more, they’ll also get access to some tasty equipment. The real Black Ops troops of the era received special treatment; they used modified and experimental weaponry, had access to alternative ammunition, and could commandeer and access vehicles and air support when necessary.

Our protagonist for example, silently took our enemy forces with a scoped crossbow, then switched to an assault rifle to clear out an enemy base. Once the action moved to the relay station, he then used explosive crossbow bolts to sow confusion, before moving in for a daring rappel and breach entrance on a fortified control room. In the second level we saw, our protagonist wielded a nasty looking shotgun firing incendiary rounds.

It’s this latter level, Slaughterhouse, that will really excite jaded CoD vets. The action begins within the burning wreckage of a Saigon building, with close-quarters fighting against a desperate enemy, then moves to a city square packed with snipers, beleaguered US troops and speeding helicopters.

This is seriously big epic stuff, and straight from the Full Metal Jacket/Apocalypse Now guide to Viet-Nam war bombast. Treyarch designed this level as a white knuckle ride from start to finish, and it turns out that those whirlybirds aren’t just for show.

Grabbing a radio from a wounded soldier, you give a pilot your code and within seconds you’re lining up targets for them to blow to hell. Treyarch wants this to be a game with moments of high-speed action cut with more intense suspense, but when the pace notches up, it’s going to be really heavy. Judging by what we saw of the Slaughterhouse level, that definitely seems to be the case.

There’s not much to say about multiplayer at the moment. We do know that there will be a discrete 4-player co-op mode, and a competitive mode with a big focus on personalisation and customisation, and a new approach to vehicular combat, which might surprise CoD3 and World at War veterans. Players will also be able to create their own classes and use them in the online battles. What Treyarch is proud of is that content from the multiplayer side has, unusually, crossed over into the single-player game: the crossbow began on a multiplayer map, and was eagerly seized upon by the single-player team, and while multiplayer maps and single-player levels don’t cross over, some elements of the multiplayer maps have made it into the single-player game.

Treyarch hasn’t always had the best press for its Call of Duty efforts. Since Call of Duty 3, the wide perception has been that the Infinity Ward entries are the gold standard CoD, with the Treyarch titles second-best. That’s not entirely fair. With World at War there were encouraging signs that Treyarch had discovered how to orchestrate huge action scenes, and the game had its share of killer moments, and some decent multiplayer options too.

What we’ve seen of Black Ops looks even better.

It’s too early to say whether Black Ops will have the stuff to compete with Modern Warfare and Modern Warfare 2 for the title of most-loved Call of Duty and anyone who tells you otherwise shouldn't be trusted. Our show and tell with other gaming journalists was a very hands-off affair, but Treyarch definitely has a vision for the game, and a desire to make it the most epic, most intense CoD yet.

If nothing else, after our meeting we’re eager to get hands-on with playable code, and see how far the studio has succeeded.

Hopefully that will be sooner rather than later.

Check out the Call of Duty Black Ops trailer.