Batman – Arkham City: How to Play as Nightwing
In Batman: Arkham City for the PS3 and Xbox 360, you can play as Nightwing on the Challenge Map stages.
First, you have to have the Nightwing Bundle Pack which is available via download.
Once the Nightwing Bundle Pack is downloaded and installed, you’ll be able to select Nightwing on the Challenge Map stages. Nightwing has his own set of moves and gadgets as well.