I was wondering what the "Game Overlay" DLC is ? I usually play non steam games through steam with the "steam controlle", but if I have the "Game Overlay DLC" installed steam fails to launch the game as a non steam game. I was wondering is this just a DLC for use with the GOG Galaxy Platform ??? If not what would I be missing with it turned off? Thanks!

It's an overlay which injects itself into the game and uses huge, ugly popups to inform you that you got achievements. You know how Steam handles it with the tiny popups to the right? Yep, Galaxy pushes it right in your face. And since by adding the game to Steam as a non-Steam game, Steam tries to add its own overlay, the two get into a fight over who becomes the ultimate overlay and the game crashes. The weird thing that this overlay is tied to the game itself as opposed to it being launched via Galaxy which is what I would expect, but I digress.

If anything, you'll get a more immersive experience by disabling Game Overlay DLC and Steam overlay will work, unless you really need to be informed whenever you get an achievement. And that's about it, really.