ZePedroPONTO: Just to be clear, I don't mean to criticise Motion Twin with my previous post. This is clearly a situation where GOG are the ones who need to step up their game and bring Galaxy to Linux.
Personally I think it's a shame that developers implement store specific features. This is what leads to these issues in the first place. People are only OK with it because steam is so dominant and it cements steam dominance because everyone who buys on another store is a second class customer who doesn't get the full game experience.
Galaxy is the crutch that GOG needs to alleviate this issue, but it's still a crutch.
Of course nothing that Motion Twin does will change that, but any game that uses store specific features is part of the problem.