Batman: Arkham Underworld was a short lived mobile game set in the Arkham universe sometime between Origins and Asylum. In the game you would play as a villain (Riddler, Harley Quinn, Mr. Freeze, Killer Croc, Scarecrow, and Bane) and command your henchmen on missions and get resources to build a hideout and upgrade your character.
In this thread I will post some concept art from this forgotten chapter of the Arkham series.