While looking at Higurashi's new Steam page, I saw that it has the OS X/Linux symbols ! http://i.imgur.com/59rG3nk.png?1 So is it confirmed ? Since I don't think you ever said anything about that before.

Since Higurashi is running in Unity, the goal is to be able to build it for all 3 platforms. Still working on making it happen, but it should be good!