so first up one has to go to the website to see the serial keys, which is insane because the gog galaxy client has not a drop down menu to show the serial keys which made me search an eternity thinking this had to be some aprils fools joke. 2nd, and this is much more important. how about you drop an cdkeys folder with a readme.txt containing the cdkey as an extra for download with the backup offline installer ?

Thing is, whether or not it's "activated" is stored in a file, so all the installer needs to do is create that file itself and save us the trouble. The key activation doesn't involve the internet in any way (as was the style at the time), so this could easily be streamlined.

The installers would have to be auto-customized on a per-user basis for that. Funnily enough, this would also mean that pirating the installer would be harder now since every installer per account now has a specific key tied to it.

I just do not see much value getting it "for free" because on sale it is almost free.. even on GoG (3-4 currencys), but indeed every game in this term got a unique key and in theory could be tracked. However, as there is no online activation i assume there is no limitation on the amount of "activations" and backup is no issue.

Manually you can do nothing, in term the key is missing... unless some sort of crack used, because the game got a unique ID generated, stored in a encrypted condition.

I do not truly enjoy but not sure it can be considered a real DRM.

I think, once the key is saved and game fully installed. You basically never have to insert the key once again, thus most likely saving you the hassle of a new input at every new install. However, you may have to backup the install-files with the key-infos, or even the whole game.

Besides: The current Steam-Version is basically equal to the GoG version, including key-demand. It can be started from the exe only, but this is a rare exception, especially for a franchise. However, GoG is the only independent shop providing this "fully capable" Doom 3 version; all the other shops are basically "Steam-providers"... somewhat funny. https://www.pcgamingwiki.com/wiki/Doom_3

So either get it on GoG or... Steam as the only other option.