[Batman: Arkham Knight coming to Linux and Mac in Spring 2016] This is due to extra development time needed to ensure good performance and wide-ranging support for Linux, SteamOS and Mac.
We would like to thank everyone who has pre-purchased the game for your support, and also for your patience while we work to deliver the best experience possible.
Obviously all the development issues surrounding Batman: Arkham Knight has caused some serious delay for the native port. And in all honesty, this does not come as much of a surprise. Linux Game News expected to see a release at the year end, but apparently there is a fair bit of work to be done. This also comes along with the recent news of Arkham Knight being re-released on storefronts.
Plus we would also like to take the time and thank Feral Interactive for keeping the community up to date regarding the release.