Batman: Return to Arkham, a compilation pack that features remastered versions of Batman: Arkham Asylum and Arkham City for PlayStation 4 and Xbox One, will launch in November at the earliest. This is according to multiple sources speaking to Eurogamer.

Return to Arkham was supposed to launch on July 26, but at the end of June, Warner Bros. Interactive Entertainment confirmed the game was indefinitely delayed.

Sources told Eurogamer that Return to Arkham was not shaping up well enough to launch on schedule. Developer Virtuous Games was apparently struggling with frame rate issues.

This matches up with what a Warner Bros. representative said last month when announcing the delay. While frame rate problems were not specifically cited, the statement mentioned that the delay was necessary to give the team more time to “deliver a polished Batman Arkham game experience,” suggesting there were some issues.

“After reviewing the progress of the project, the team at WB Games has decided to delay the release of Batman: Return to Arkham to give the team at Virtuous Games additional time to deliver a polished Batman Arkham game experience,” reads the statement.

“We do not have a release date yet and will be sure to communicate that once we are sure the game will be ready. We know this is disappointing news, but we feel the extra time will allow the team to create the best gaming experience for our fans.”

Following multiple leaks, Batman: Return to Arkham was officially announced in May. In addition to the base games, players will receive all Game of the Year extras and downloadable content. Overall, Warner Bros. said players can expect “improved graphics” and “upgraded models, environments, lighting, effects, and shaders.”

While the original games were powered by the Unreal Engine 3, the remasters are being developed by Virtuous using Unreal Engine 4.

Virtuous previous worked on Heavy Rain‘s PS4 version and contributed to Uncharted 4: A Thief’s End. Additionally, the company created assets for Star Wars: The Force Awakens.

Take a look at this Batman: Return to Arkham screenshot comparison gallery to see some of the visual differences between the old and new versions of Rocksteady’s games. These comparison shots are not official, and were compiled by a fan.