Batman: Arkham City builds upon the intense, atmospheric foundation of Batman: Arkham Asylum, sending players flying through the expansive Arkham City - five times larger than the game world in Batman: Arkham Asylum - the new maximum security "home" for all of Gotham City's thugs, gangsters and insane criminal masterminds. Featuring an incredible Rogues Gallery of Gotham City's most dangerous criminals including Catwoman, The Joker, The Riddler, Two-Face, Harley Quinn, The Penguin, Mr. Freeze and many others, the game allows players to genuinely experience what it feels like to be The Dark Knight delivering justice on the streets of Gotham City.

Batman: Arkham City - Game of the Year Edition includes the following DLC:

Catwoman Pack
Nightwing Bundle Pack
Robin Bundle Pack
Harley Quinn’s Revenge
Challenge Map Pack
Arkham City Skins Pack


Batman: Arkham City - Game of the Year Edition packages new gameplay content, seven maps, three playable characters, and 12 skins beyond the original retail release:

Maps: Wayne Manor, Main Hall, Freight Train, Black Mask, The Joker's Carnival, Iceberg Long, and Batcave
Playable Characters: Catwoman, Robin and Nightwing
Skins: 1970s Batsuit, Year One Batman, The Dark Knight Returns, Earth One Batman, Batman Beyond Batman, Animated Batman, Sinestro Corps Batman, Long Halloween Catwoman, Animated Catwoman, Animated Robin, Red Robin and Animated Nightwing

System Requirements
Windows
Mac OS X

OS: Windows XP, Vista, 7
Processor: Intel Core 2 Duo 2.4 GHz or AMD Athlon X2 4800+
Memory: 2GB RAM
Hard Disk Space: 17 GB free hard drive space
Video Card: ATI 3850HD 512 MB or NVIDIA GeForce 8800 GT 512MB
DirectX®: 9.0c

https://store.steampowered.com/app/200260/Batman_Arkham_City__Game_of_the_Year_Edition/