A spin-off game titled Batman: Arkham City Lockdown was developed by NetherRealm Studios for iOS and was released on December 7, 2011. Taking place before Arkham City, the game sees players using touchscreen controls to fight enemies one-on-one, including villains such as Two-Face, Solomon Grundy, Joker, and the mercenary Deathstroke. Defeating enemies earns points that can be used to upgrade Batman's stats or unlock gadgets or costumes.
After the announcement of Arkham City, a new super-prison in based in the decaying urban slums of Gotham City, by Mayor Quincy Sharp, the Joker breaks out from Arkham Asylum, joined by several other villains, who cause mayhem in the streets of Gotham. Intent on stopping the escapees, Batman first goes after Two-Face, defeating him and his gang on the streets, soon defeating Penguin and his gang, who have escaped from the Blackgate Penitentiary, and Solomon Grundy in the sewers as well. He is later attacked by the assassin Deathstroke and his goons, hired by Hugo Strange, the warden of Arkham City, at the Steel Mill, but Batman prevails and leaves them to be arrested and incarcerated at Blackgate, while Strange formulates a new plan to defeat the Dark Knight in the future.
