Attention Mac owners: I'm pleased to announce that Legionwood has now been ported to MacOS, thanks to the efforts of Jammed Gears Productions, a Youtube based team whose mission is to make indie games more accessible to non-Windows players. I don't know much (if anything) about Mac systems, so I'm not sure how this port was made possible, but it sure is impressive to see Legionwood running almost flawlessly on a MacBook.
You can grab the port here. You should be able to play the game just by clicking on the "Legionwood.app" file contained within the archive. Please keep in mind, however, that this conversion was developed by an external team, and unfortunately I can't offer support or updates for any errors you may encounter.