In an interview with Famitsu, Kingdom Hearts director Tetsuya Nomura explained the meaning behind the number “2.8” in the title of the recently revealed Kingdom Hearts HD 2.8 Final Chapter Prologue.
The games included in Kingdom Hearts HD 2.5 Remix are set before Kingdom Hearts Dream Drop Distance, so that game is “2.6” in the series. Since Kingdom Hearts χ Back Cover/Kingdom Hearts Unchained is supposed to be the first game in the mainline series, that is being represented as “0” in the collection. And lastly, Kingdom Hearts Birth by Sleep is “0.1” and that then leads into Kingdom Hearts 0.2 Birth by Sleep -A Fragmentary Passage. Add 2.6+0+2.8 and all three titles in the collection will equal to 2.8.
Kingdom Hearts HD 2.8 Final Chapter Prologue was announced last week for PS4 and is planned to release next year.