There are 13 games in the Kingdom Hearts timeline.
Kingdom Hearts HD 2.8 Final Chapter Prologue Review
Walkthrough - Kingdom Hearts Guide - IGN
Walkthrough - Kingdom Hearts: Birth by Sleep Guide - IGN
Kingdom Hearts: Birth by Sleep - IGN
Kingdom Hearts HD I.5 and II.5 ReMix - IGN
Kingdom Hearts HD I.5 ReMIX - IGN
Kingdom Hearts [V Cast Mobile] - IGN
Kingdom Hearts HD 2.5 Remix - Wikipedia
Kingdom Hearts Games - IGN
Mini Games Guide - Kingdom Hearts 3 Guide - IGN