The whole Kingdom Heart franchise feels like a mess. Currently, there is the Kingdom Hearts 1.5 HD Remix and Kingdom Heart 2.5 HD Remix which was both released on the Playstation 3 and then there is the upcoming Kingdom Heart 2.8 which will be released on the Playstation 4.
The Kingdom Hearts 1.5 HD Remix will consist of Kingdom Hearts 1 , Chain of Memories and 358/2 Days. Kingdom Heart 2.5 HD Remix will consist of Kingdom Heart II, Re: Coded and Birth by Sleep while the new Kingdom Heart 2.8 which consist of Kingdom Hearts 3D: Dream Drop Distance, Kindom Hearts Unchained X as well as O.2: A Fragmentary Passage.
There are not rumors saying that Square Enix might be working on a Kingdom Hearts Playstation 4 Collection which will most likely compile everything into one. While Square Enix did not confirm the rumor, they did that they are not going to rule it out which means you might want to wait a little longer before buying the Kingdom Hearts 2.8.
