Anyway, in some other discussion someone else claimed that some pirate lady has been able to re-compress GOG installers to something like 30% of the size of the original GOG installers. I'd just like to hear about the technology there, how does she achieve that, or does she leave some data out? Or was it just a rumor and hearsay, not true at all?
Whilst I've not gotten it that far I have managed to reduce the installer size for Deus Ex Mankind Divided yesterday.
The size for the base game unmodified GOG installers is 34.7GB, the Season Pass unmodified GOG installer is 10.4GB, so in total for both its about 45.1GB.
I extracted the game from the original installers using innoextract, removed the language packs (which saved about 10GB) then added the Season Pass files to the base game then created my own Inno Installer for the whole lot which in total sits around 31.5GB.
I could most likely get it smaller if I knew more about compression.
And also creating it myself means I know what its doing, and it doesn't have a lot of the bloat that GOG installers have.