Barry_Woodward: Is it a Steam exclusive by default or is Valve following Epic Games Store's lead by buying exclusivity?
Nah, valve has nothing to do with it. Heck, valve is already against egs exclusivity and decided to not follow such steps.
Imho it's just xseed not wanting to handle the online functionality through galaxy api. They quickly gave up despite announcing (and then cancelling) a senran kagura game coming on GOG, basically saying that it required to rebuild the MP portion of the game and that
it wasn't worth the hassle.