Van der Leeuw said that the "bulk" of the first-person shooter's 39.7 GB is made up of high-res textures designed exclusively for the PlayStation 4.
"I think at some point the disc image that we were generating was around 180 GB," van der Leeuw said. "And if we would have put all the levels in, which we didn't, because then the disc image generator broke, it would have been around 290 GB of data.
"So we had to completely re-architect how we deal with data. And we did a lot of work — this is actually something I'm extremely proud of — to optimize our disc access pattern. Sony made special libraries for us because we were the first ones hitting these sort of problems. I think it's something that a lot of people will need to be doing in future."
Those who purchase Killzone: Shadow Fall through the PlayStation Store will be able to begin playing after the first 7.5 GB have downloaded. Sony engineer Neil Brown said in July that players would able to play "at least the first section" of a game as it downloads. Microsoft's next-gen console, the Xbox One, will have a similar feature.