The game is a Steamplay title now and for a little more than another 24 hours as of this writing there is a bundle deal with the game and its DLCs for 10 bucks or if you prefer, just the game itself for $7.50. It's normally twice that. I noticed the DLCs are not flagged as being Steamplay and I posted a question about this on the Steam forum but have not gotten a reply yet. I suspect it is just an oversight but I could be wrong of course. If I don't find out in time I think I'm going to go for the bundle anyway and hope for the best. The worst thing that can happen is a I contribute an extra $2.50 to the cause of a developer who chose to support the Mac with the main game at least. Now we need a Mac version of Path of Exile! I did post a request for that in the relevant Steam forum and one of the developers was nice enough to reply and say it was under consideration but they couldn't say more at this time. So I am hopeful!