Call of Duty: Ghosts developer explains the difference between an upgraded engine and an entirely new one

The engine used to power the upcoming Call of Duty: Ghosts is an evolved version of a last-gen engine and will feature remnants of developer Infinity Ward's last engine, animation lead Zach Volker told Official PlayStation Magazine.

According to Volker, developers cannot create an entirely new engine from the ground up within a two-year cycle. The result is simply a highly upgraded form of an earlier engine; however, with enough major overhauls, this upgraded engine often has little in common with its predecessor.

"When we're talking about a new engine we're talking about upgrading significant systems within in that engine," he explained. "We're not talking about throwing it all away and saying we're starting from the ground up."

Volker went on to describe the difficulty of making distinctions between an updated engine and an entirely new one. New engines are built out of necessity, he explains: "So looking at our current situation, focusing more on the next generation of hardware, we are now going to have the bandwidth to build many more things and our engine just can't handle as much as we'd like to throw at it right now. And that necessitated the need to go onto a new engine."

"What we do is we say ‘okay what are the things that are significant and that we would say that are encompassing of the engine or its visual quality? Are those being upgraded in a significant way? Alright then, I think that warrants that we've got a new engine on our hands."

According to Volker, the original engine years ago was built on Quake engine, however the team has created so many new engines and overhauls to the original tech "that I'm not sure any of it still exists."

Call of Duty: Ghosts, the long-rumored next entry in the Call of Duty franchise, became official earlier in the month. The title, itself a new sub-brand for the franchise, is said to feature a new engine and new ideas.