French film star Vincent Cassel dubs Napoleon Bonaparte’s voice into English for a new video game set to release on Tuesday, which sets the French emperor on a violent quest to take over Eastern Europe.

Valor Mortis, developed by Polish studio One More Level, shows Napoleon’s 19th-century army fuelled by a mysterious substance that makes them stronger before turning them into zombies and half-animal creatures. Much of the action is straight out of a blood-soaked horror film.

One More Level co-founder Radoslaw Ratusznik said the studio originally approached agents for Cassel — who starred in Ocean’s Twelve and Black Swan as well as a host of award-winning French movies — to do the voiceover as “a joke”.

“We reached the agent and we had some conversations. And they were on board. And we were, ‘oh, my God, that’s so amazing’,” Ratusznik said of the team’s surprise when Cassel agreed.

Cassel said he had been tempted because, like Napoleon, he has Corsican roots.

“It did ring a bell for me because I’m from Corsican origins on the side of my mother, and I always heard about Napoleon at home, and you know, as a lot of Corsican people, you know, in their house, they have a lot of portraits of Napoleon, so that’s how I grew up somehow,” the 59-year-old actor said in a promotional video for the game.

“My grandmother and my auntie used to tell me that he’s a cousin of the family. Cause you know, it’s a very small island, Corsica.”

Cassel does not discuss having to make Napoleon speak English, but Ratusznik said it was a commercial choice for the studio based in Krakow, which is known for having developed Ghostrunner.

“As a small team, we have to make tough decisions about what we can ship,” he said, adding that French voices will only be added if there is enough demand.