Kicking off with a mission to assassinate Fidel Castro, the newest installment of the hit "Call of Duty" franchise went on sale in North America and Europe Tuesday taking gamers on a series of Cold War-era military adventures.

"Call of Duty: Black Ops" is the successor to "Call of Duty: Modern Warfare 2", last year's biggest grossing console game with more than 20 million units sold around the world.

Expectations for the Cold War chapter are high: IT marketing firm IDC forecasts that 11.7 million copies will be shifted in the United States by the end of the year alone.

"Black Ops" marks a significant change for the franchise, ditching World War II and modern-day environments for a Cold War theme.

Mission number one is to assassinate Cuban President Fidel Castro before the 1962 missile crisis in the communist Carribean nation, the moment when the Cold War came closest to tipping into a full-blown nuclear conflict.

From then on, missions take gamers inside the former Soviet Union and southeast Asia during the Vietnam War.

But while the setting is new, developers stick to the franchise's signature formula of varied gameplay in highly explosive environments.

The 18-rated game opens with an animated sequence in which the main character, US special forces agent Alex Mason, suffers torture at the hands of enemy combatants.

Gamers then take control of a host of weapons, vehicles and even helicopters to complete a string of increasingly complex missions.

"We wanted the gamer to feel totally immersed in playing the role of special forces behind enemy lines on top secret missions. That is why we have a lot of cut-scenes," said Dominique Drozdz, head of animation at developer Treyarch.

To increase realism, the studio used motion capture technology to recreate ultra-accurate body and facial movements, while Vietnam veterans were consulted on how they modified weapons or infiltrated enemy lines on dangerous missions.

"We were also able to find a Russian soldier who showed us special techniques used by Spetsnaz," said Drozdz, referring to the Russian special forces units.

The game offers the option of 3D play for users with a compatible TV set.

The "Call of Duty" franchise has been at the forefront of a massive expansion in online gaming, and while "Black Ops" offers a fairly modest eight hours of one-player missions, the online multiplayer version offers a string of extras.

"'Modern Warfare 2' was the most played online game on Xbox 360 and Playstation 3. It is important to continue this," said Guillaume Lairan, the head of French marketing for publisher Activision.