It's a surprise that these weren't cancelled before, given how many issues Warner Bros had with the PC port of Batman's adventure. But at least today it's official: there won't be a Mac or Linux port for Arkham Knight.
In a Steam announcement, the developers said those who had pre-ordered the Mac or Linux ports of the game could request a refund through Steam.
Some users responded by hoping Arkham Knight might be ported at a later date, but it's difficult to imagine that ever, ever happening given the game's torrid history on Steam. The game's worthy of being mentioned in the same sentence as Ashes Cricket 2013 for a reason, after all.