New Zealand's iOS App Store, which serves the dual functions of selling apps to New Zealanders and giving us advance warning of upcoming releases in the rest of the world, is home to a new Batman: Arkham City spinoff for iPhone and iPad.

Batman Arkham City Lockdown is a one-on-one fighter developed by Mortal Kombat's NetherRealm Studios, in which Batman beats up the Joker, Two-Face, Solomon Grundy, Deathstroke, and other villains who appeared in the main game. You'll be able to upgrade Batman's abilities, and dress him in different skins.

IGN speculates it's an Infinity Blade-style fighter, though a screenshot on the App Store promises "unique gameplay in every boss fight." With the game out now in New Zealand (for NZ $8.29, about US $6.45) we'll likely see it tonight or tomorrow in the rest of the world.