Kyle Higgins, writer of the current Nightwing series, tweeted this not too long ago, "Nightwing playable in Arkham City? HELL YES." He included a link to GameRant.com with some details. We already know that besides Batman, the game will have Robin and Catwoman as playable characters (playing as Tim Drake requires a special pre-order, at least for now). Rocksteady Studios had let it slip that there would be a fourth playable character as well.
Over at PS3Trophies.org, some achievements were posted detailing which belong to Batman, Catwoman, Robin and Nightwing. The two with Nightwing are titled "Nightwing Revenge" and "Campaign Nightwing." It doesn't look as if Nightwing would be featured in Arkham City's campaign but there's always the chance for episodic DLC.
Nightwing would also require a separate set of moves as his fighting style with batons and acrobatics is different than Batman's. The game will be released on the major platforms October 18. Who isn't excited for this?
Some screenshots have turned up apparently from the alpha stage (without additional graphics processing). Is this what you would expect Nightwing to look like in Arkham City?== TEASER ==