MarkoH01: I just tested it:
For the remaining DLCs from Dying Light to be installed you don't need Galaxy at all. That is all good there is to say to it.
If you install the game using the offline installer and start it offline you will see 8 DLCs listed.
If you install the game using the offline installer and start it online you will see 13 DLCs listed.
Go offline again and start it again and the DLCs will be missing again.
Without being online while starting the game it is not possible at all to access the remaining DLCs. The game simply seem to behave different the moment you are going online.
powergod: As far as I know, the game itself has no online capabilities without galaxy installed...
How can you "start it online" without the galaxy service running ?
The game was always offline for me until I installed Galaxy. (I actually installed it just to solve this particular issue)
And to be clear, even games with offline installers use galaxy by default if it's installed.
To make it more clear:
I deactivated my net and started the game which I installed using the offline installer. I looked into the "What's new section" and saw 8DLCs listed. I then activated my net and restarted the game - 13 DLCs listed. Deactivated it again and it showed 8DLCs again. No Galaxy involved. I did not test if I could access those DLCs even though they weren't listed.
powergod: And to be clear, even games with offline installers use galaxy by default if it's installed.
Not true. Usually if you start the game using the executable without having Galaxy started the game does not use Galaxy. However there are some games that still use the online capabilities of Galaxy (like i.e. GWENT) so to make sure this won't happen, I renamed the Galaxy folders as well.
In the end however I don't think that it is important if Galaxy is needed or not since it's clear that you need to be connected. Otherwise there is no way to access the DLCs at all even if you already have been online once to activate them. The additional files don't change a thing as long as you are offline.