This is the first Kingdom Hearts game released on a Nintendo platform since Kingdom Hearts 3D: Dream Drop Distance (2012).
While the version of Sora used during gameplay uses his outfit from the original Kingdom Hearts outfit, however as this game reproduces cutscenes from the series, the other outfits from Kingdom II, Dream Drop Distance, and III also appear in this game.
Similar to Dream Drop Distance, this game also recaps storyline material from previous games. Several differences are that instead of using text like DDD did with the Chronicles section of the Mementos, it uses actual cutscenes from those games with Kairi serving as the narrator, and the other difference is adding more material that was not part of the DDD's Chronicles which not only includes DDD itself, but also 0.2 and KHIII as well.
As numerous levels were used in more than once in previous games, instead of having one respective world for each, multiple versions of those worlds are used to separate the music to that are limited to that version, which also includes any differing level design for that respective version. One example is Neverland due to using different music and level designs between Kingdom Hearts (2002), Kingdom Hearts: 358/2 Days (2009), and Kingdom Hearts: Birth by Sleep (2010). Other examples are Traverse Town and Hollow Bastion/Radiant Garden.
For the world based on Re: Coded, it only uses System Sector grid material from the original game as the background, as it is the only aspect of the game that was new and not based off a previous title.
Most of the levels in this game uses custom-made stages based off the level designs of that world from that respective previous game that music track originated from excluding the Keyblade Graveyard with the KHIII tracks due to its previous inclusion in Birth by Sleep. Due to the higher degree of graphics used in Kingdom Hearts III, their newer levels instead had their backgrounds based off the cutscenes from their respective world.
This is the first game in the series to mainly focus on Kairi, who had primarily served as a supporting character in the previous games and was only briefly playable for a boss battle in the Re: Mind DLC of Kingdom Hearts III.
The One-Winged Angel Track is listed under "Kingdom Hearts Final Mix" tracks. This is because though it was also part of the original game, the fact was the Sephiroth battle was only part of the international release and not the original Japanese release, and was first made available in Japan for the Final Mix release which added the hidden bosses that were originally part of the original games' international release.