"The environments, the levels, the soundtrack all give a strong feeling of descent - each encounter, each level becoming progressively more hellish. Most importantly though, we've expanded the legions of Nazi undead with some really intimidating new enemies which we'll reveal soon."

While the game has only been confirmed for a PC release later this year, Rebellion also hinted at releases on Xbox One and PlayStation 4.

"Now there's the possibility," said Rebellion boss Jason Kinglsey, referring to the self-publishing policies available to developers. "Before the wasn't really the possibility of self-publishing, so you couldn't even begin to think about it. You had to go via a third party and do a deal with somebody else. It made it less and less attractive.

"Nazi Zombie Army was a gamble, really. We didn't know whether it would work. We hoped people would like it. We hoped people would take it in the slightly tongue in cheek way it was meant with the title. And we obviously didn't have much money to market it.

"So we just put it out there and it's been very very good business and we've created a lot of fans who just like a straightforward gory shooter against zombies. It pretty much made its money back on the day of release. That was awesome."

Rebellion announced Sniper Elite 3 in March. It will release for current and next-gen consoles in 2014.