Bethesda Game Director Todd Howard explained in a separate interview with IGN that his game would not use id Tech 5. The studio's new engine built for its upcoming title is more beneficial to creating huge, open-world games, such as Fallout 3 and The Elder Scrolls IV: Oblivion, while id Tech 5 is better for more contained environments.
"We decided to really reboot our technology after Fallout 3, so we had been making plans for that and started doing some things. The id thing came along later, so it's a mix of that plus the kinds of games we do are a bit bigger and more dynamic.
"Id Tech 5 is the best thing in the world at doing a very static environment that looks pretty and you're going to run through. But for the kinds of things I like to do, I like the world to be more dynamic."