
Every cutscene from Kingdom Hearts 358/2 Days, whether it was originally a prerendered scene or used in-game graphics, would be remade for Theater Mode. The only exception is the cutscene with Unknown, as it used lines recycled from other cutscenes, just like the ones from the English version were used for this cutscene for the original Japanese PS2 release. The cutscenes from Kingdom Hearts Final Mix, which used English voice acting, would use the original Japanese voice acting, though the Final Mix-exclusive cutscenes would still remain silent for both versions, much like with the original release. It was revealed that the character models from Kingdom Hearts 3D: Dream Drop Distance, like Sora, Riku, and Ansem's for example, are being used in Kingdom Hearts HD 1.5 ReMIX as a base for the game's characters. In September 2012, Square Enix announced Kingdom Hearts HD 1.5 ReMIX.

Plans for an HD re-release were further hinted in a Secret Message in Kingdom Hearts 3D: Dream Drop Distance, unlocked during the credits. The idea for a high definition re-release preceded plans for a Final Fantasy X re-release, and was a focus for two Square Enix programmers for over a year.

It includes full HD remasters of Kingdom Hearts Final Mix and Kingdom Hearts Re:Chain of Memories with added PlayStation 3 Trophy support.

Kingdom Hearts HD 1.5 ReMIX, stylized as Kingdom Hearts HD I.5 ReMIX, is an HD remaster compilation of the Kingdom Hearts series, made in celebration of the series's tenth anniversary.
