You've probably heard mention before about Call Of Duty running on an old Quake 3 Arena id Tech 3 engine. And it is in a way, but with revisions and upgrades for almost every game in the series, the idea of a 'COD engine' is hard to pin down.

"Engines are funny things," Black Ops 3 multiplayer director Dan Bunting tells me. "People used to talk about game engines as if it was a singular product that the game’s built on. But engines are really collections of tech that have some very basic, fundamental architecture to them". He does concede that, "the core architecture of the game is still based on the technologies that it’s been built off of," but makes it clear that: "most engines in the game industry, for large scale games, have all come from a lineage back to an earlier game engine".

So, in COD's case while there might be a few lines of Quake code floating around in there somewhere, it's unlikely. The engine's been revised and updated for each instalment, building on original tech and adding new features. Everything from ragdoll physics and "console support" if you go back as far as COD 2, through to whatever the latest fancy lighting schtick. "Engines these days, especially for games of this kind of scope, are very varied, so that each component of the game has its own engine in a lot of ways," he explains. "The engine itself, what the people refer to the as the engine, is the technology the studio develops along the way".

@treboruk92 Heavily modified from BO2 including completely new renderer.May 1, 2015

For example, Black Ops 3 took advantage of the new three year development window to significantly update its old Black Ops 2 engine (that's Treyarch's director of development up there, tweeting about the lineage of the new technology). "We had a lot of tech overhaul we had to do," says Dan. "We had to basically re-engineer our graphics engine, we had to re-engineer our AI system. There was a lot of tech work for the transition to the next-gen platforms to really capitalise on the power".

And that tech grunt isn't just about looking pretty either, he points out: "The responsiveness is something that’s really close to the heart of this game; millisecond scales. Being able to run at 60 frames a second, and being able to render the kind of stuff we render on screen, is impressive".

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