Kingdom Hearts Dream Drop Distance HD
The collection features an HD remaster of Dream Drop Distance, which Nomura stated was essentially a full remake of the game, since the original utilized the two screens of the Nintendo 3DS.

Kingdom Hearts χ Back Cover
Further information: Kingdom Hearts χ
Kingdom Hearts χ Back Cover, told through HD cinematics, tells a new tale of the Foretellers and reveal new parts of the series' history. Nomura revealed that Back Cover would utilize technology being developed for Kingdom Hearts III.

Kingdom Hearts 0.2: Birth by Sleep-A Fragmentary Passage
Further information: Kingdom Hearts Birth by Sleep
Kingdom Hearts 0.2: Birth by Sleep–A Fragmentary Passage is a new, short episode taking place after the events of the original Birth by Sleep, told from the perspective of Aqua. A Fragmentary Passage, which ties into Kingdom Hearts III and uses technology from III, is set immediately after Dream Drop Distance, when King Mickey reveals that he has a few secrets to confess, relating to Aqua and her time in the Realm of Darkness. The story then picks up immediately after the secret ending of Birth by Sleep Final Mix, and will last about the length of one world from the series.