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.