Feral Interactive has just announced that one of the biggest releases of 2011, and sequel to the intensely popular Batman: Arkham Asylum [review]; Batman: Arkham City is coming to Mac next month. Pricing, system requirements and an official release date are unconfirmed, but the additional Harley Quinn’s Revenge add-on as well as the Catwoman, Nightwing and Robin packs will be purchasable from inside the app.

Batman: Arkham City builds upon the framework laid down in its predecessor, allowing players to glide ‘through the expansive Arkham City, [which is] five times larger than the game world in Batman: Arkham Asylum‘. Familiar faces like the Joker, Harley Quinn and The Riddler return in Arkham City, as well as some newcomers to the game series; Two-Face, The Penguin, Mr Freeze and more.

We’ll keep you updated as soon as Feral Interactive release more info about this release.