Sony has given a fresh update on Team Ico's progress with The Last Guardian.
Worldwide Studios boss Shuhei Yoshida told Eurogamer that Sony Japan Studio was forced to re-do some work on the PS3 exclusive, but that progress is being made on technical issues.
"The team is still working on it very hard," he said. "There are certain technical issues they've been working on. That's the period of time when the game, looking from the outside, doesn't seem to be making much progress. But internally there is a lot of work going into creating the title.
"We had the game playable. At one point we felt that it would be produced for a certain time period. That was the time we prematurely talked about the launch window. But it turned out the technical issues are much harder to solve. So the engineering team had to go back and re-do some of the work they had done."
Asked if The Last Guardian is now a PlayStation 4 project, Yoshida replied: "The game is developed on PS3."
PlayStation software development head Scott Rohde said in June that the game "will ship when it's absolutely ready".