Batman: Return to Arkham was a long rumored project that Warner Brothers finally unveiled not that long ago, the collection was to include a remastered version of Arkham Asylum, as well as Arkham City with a release date set for July 29th. However, Batman will not be seeing this release date, and as it turns out we have no clue when this game will actually arrive.
Warner Brothers Interactive's Steve Grayson has announced the delay for the game via their official forums, wherein they revealed that Virtuous Games who are handling the remastering duties for the game have needed to have more time. The team at Virtuous Games have needed more time as Grayson has said that they need “additional time to deliver a polished Batman Arkham game experience.”
Unfortunately this has received an indefinite delay so we are going to need to wait for a new update on when we will see it.