WinterSnowfall: Looking on the bright side, the Linux "installer" is actually a .tar.gz archive.
muntdefems: Really? Hahahahaha, that's a good one! Yep, going back to compressed tarballs would be good news indeed.
I just wrote an
unpack_gog_game.py wrapper script which uses
unzip to extract
data/noarch/* from the Zip file at the end of the MojoSetup bundle into a folder named after the installer.
Sure, it disqualifies my install from technical support if I didn't actually run the installer, but it's far less bothersome than putting up with interactive installers that don't remember my preferred games folder and clutter up my launcher menu and I've never needed to contact tech support anyway.
(I keep a lot of games installed and neither LXDE nor KDE subcategorize the Games folder, so it's easier to dogfood my experimental "Steam client-alike which doesn't require a service" project.)
So far, I've only heard of one game where some kind of post-unpack script had to be run for the Linux version (yay, lack of a Registry), it was contained within the game folder (I think it was in the "support" folder next to "icon.png" and "gog.com.shlib"), and I remember it being expensive enough that it probably still hasn't come on sale cheaply enough for me to consider buying it.