Rocksteady Studios marketing manager Guy Perkins said that it was simply a matter of ensuring that the game would be up to the desired standard, said the Hollywood Reporter.
"We feel that we have an absolutely awesome game in the works, and we want to make it as great as it possibly can be. We just need more time to do that," Perkins said.
Perkins also explained Rocksteady's decision to skip Arkham Knight releases for the Xbox 360 and PlayStation 3 platforms, saying that older hardware could not handle the game's needs.
"Gotham City is five times larger than the game world of Arkham City. And by virtue of having a bigger city, you need more memory and more horsepower to just make that happen," he added.