On their Ulule page, in the FAQ, they were asked what platforms they will support and they said PC, Mac, and Linux.

What platform will the game be for?

We are currently creating a version of 2Dark forPC, Mac and Linux. We may also create a version for console or tablet, but we can't make any promises about that right now.

http://archive.is/QKA91

After the game was shipped they were asked on their Steam message board when Linux will come out and they replied with...

Sorry, but there is no Linux version planned yet

http://archive.is/6v8Zg