Meanwhile, Mamais confirmed that the version of Witcher 3 shown during Microsoft's E3 press conference was indeed running on an Xbox One at 900p resolution and 30 frames per second.
It looked pretty good to our eyes, but Mamais insisted it will end up looking even better by the time development is finished for Witcher 3's February 2015 release date.
"We're still optimising for Xbox One and PS4 so it should look better than that in theory," he said. "But everything we're doing optimisation wise for PS4 and Xbox One, we're also optimising for PC. It's a cross-platform engine, so any optimisation we do for one platform goes into the other platform and just speeds it up, basically."
A 900p resolution is CD Projekt's "minimum", Mamais said. "We will hit 900p no problem. We'd like to get it up to 1080p on Xbox One. That's our goal. Whether we can do it or not I don't know. We've got to squeeze everything we can out of the hardware.
"Microsoft and Sony say 900p is the sweet spot, and there's not a lot of difference visually between 900p and 1080p, but it's a hot topic now. So that's what my goal is."
To this end, CD Projekt is working directly with Microsoft engineers to try to improve the game's performance on Xbox One.
This month Microsoft updated the Xbox Development Kit (XDK) so games that are not using skeletal tracking with Kinect can choose to use the portion of the Xbox One's graphics processing unit that was previously reserved. Now, games have access to 100 per cent of the Xbox One GPU for increased resolution and graphical effects.
Mamais said CD Projekt had yet to take the new XDK out for a spin, but it will, as Witcher 3 does not use Kinect motion.
Witcher 3 does support voice control via Kinect for magic signs so players need not access the radial menu. But as Eurogamer reported yesterday,
voice control remains in use if players have a Kinect despite the Xbox One update.
"The voice command side doesn't tap into the GPU side at all, so we can still have Kinect," Mamais said.
"So if you buy Kinect you can use it for voice commands and system commands. It's modest integration for voice. But since it's not using the camera at all we can use any extra power we can take to speed up the GPU."
As expected, on PlayStation 4 Witcher 3 outputs at 1080p resolution.
"It's just a slightly more powerful machine," Mamais said. "That's pretty known. But I think in the longer run everything is going to be on both platforms running at 1080p. It's just taking developers longer to do it than they expected because the architecture is a little more challenging on the Xbox One.
"It's actually easier to develop for Xbox One for us because we're PC developers. So everything we do on PC is for DirectX 11. And Xbox is also based on DX. So for the rendering side it's a more natural progression for us to go to Xbox.
"But we anticipate being able to do 1080p on PS4 a little bit easier than on the Xbox."