Sony Worldwide president Shuhei Yoshida has refused the chance to categorically confirm that The Last Guardian will still definitely be released.
The game – a spiritual successor to PS2 (and subsequently PS3) hits Ico and Shadow of the Colossus – was first revealed at E3 2009.
However, development has been troubled and not helped by the departure of former lead designer Fumito Ueda.
"When we have confidence in saying that, we will talk about it," Yoshida told Eurogamer when asked if the game will still definitely be released. "But today, we are working through some engineering effort.
"The team is back in Tokyo is working hard, and there are some technical difficulties that the team is focused on right now. That's why we don't have an update."
He also refuted accusations that perhaps it is being held back for the expected launch of PS4 next year.
"What does that question mean,” he said when asked if The Last Guardian is still a PS3 game. “It is a PS3 game.”