Square Enix's upcoming Kingdom Hearts III is no longer using an in-house engine, instead opting for Unreal Engine 4.
"Development is steadily proceeding as planned," he told Famitsu. "Due to the impact of changing the game engine to Unreal Engine 4 – which we did for various reasons – there is some difficulty rendering images. And with the full support of Epic Games, we'll be able to progress smoothly."
Previous Kingdom Hearts have been developed with in-house engines, and Square Enix is still using its own tech for Final Fantasy XV.
Epic Games launched Unreal Engine 4 earlier this year, with the interesting new business model of making everything available – including the source code – for a low monthly fee.