Hate to have to use the S word, but Steam does have a Linux version of the game.

Why is this not on GOG? Are there any plans on making it available?

Mainly that it was released here before GOG carried Linux games. They are adding, if slower than we would like, Linux versions of the existing catalog. Most recently a bunch of the Tex Murphy games.

That is true, they are getting added... ever so slowly. It's been a while since they added Linux support, so I was expecting this to come out a lot sooner, as it already has a working Linux version available (I had honestly hoped it would be included in the first Linux-version batch of games they released). *Sigh*.

Guess I'll have to wait and see.

Yeah, I would have thought it would be low hanging fruit myself. Most cases I believe they need to rework their agreement to include distributing the Linux version.