2 books in series

Batman: The Arkham Saga

Batman: The Arkham Saga is a 6-book series with 2 released primary works first released in 2013 with contributions by Derek Fridolfs, Paul Dini, Adam Beechen, Doug Wagner, Peter J. Tomasi, and Alexander C. Irvine.

Batman: Arkham Unhinged, Vol. 1
Batman: Arkham Unhinged, Vol. 2
Batman: Arkham Origins
Batman: Arkham Knight, Vol. 1
Batman: Arkham Knight, Vol. 2
Batman Arkham Knight: Genesis
Batman: Arkham Knight - The Riddler's Gambit