While I like GOG, I must say that they don't support linux, they merely sometimes make it possible to download binaries which may work on linux if you do everything yourself.
I tried, but not every game works out of the box yet. Sometimes you need to do a lot of work to play a game on linux, on windows you just click "next" several times. Also, they don't provide linux launcher, you first have to find that you can indeed download those games manually, navigate to your library in a special way and then you can download something that might work.