There's still a lot of room in the Killzone universe to expand and to do new stories, he said. "We want to leave ourselves open like [the ending of Killzone 3] because Killzone's not going to go away anytime soon." Managing Director Hermen Hulst backed up ter Heide, adding that the studio has plenty of ideas left for the franchise. "We've had our Pearl Harbour moment, our D-Day moment, but there are so many different types of war, different kinds of conflicts that have originated from different reasonings, from a different rationale."