From Console To Handheld: Unexpectedly Portable Video Game Sequels (Modojo)

Chris Buffa (Modojo): When a console game gets a sequel, this title normally appears on a console. Publishers release companion games on portables (Square Enix's Kingdom Hearts series is a perfect example), but for the most part, these companies won't make part two or three handheld exclusive.

Well, except for those rare occasions when they do.