Maxvorstadt: I downloaded the game via GoGdownloader and don`t use Galaxy at all. Also, the game is Singleplayer.
So why is there a Galaxy.dll in the game directory? Is this a clue that Galaxy shall become the same as the Steam client? From optional to necessary to play games from GoG?
A DLL is a dynamic link library, which provides access to an API (application programming interface). Applications are almost always linked dynamically to all of the libraries they use in order to optimize memory usage (shared memory) among many other benefits. When the application starts, the operating system's dynamic linker will demand load all of the libraries that are linked into the executable to resolve symbols present in the application. In order for the application to load successfully all of the DLLs that the application is linked to need to be present on the system and available to the dynamic linker.
galaxy.dll is the dynamic library provided by GOG that implements the Galaxy API, which is the collection of software interfaces that allow programs to communicate with Galaxy services, track game time, achievments and other back end services. Whether or not someone uses Galaxy client, and whether or not someone uses any of the features provided by the GOG Galaxy API such as achievements for example makes no difference. Any piece of software that dynamically links to any library must have that library present on the system when it is executed so that the dynamic linker can resolve the symbols. This is just how operating systems load executables into memory for the last 20 years (in Windows at least). It works the same way in other operating systems as well. In Linux the dynamic linker loads *.so files rather than .dlls, etc.
So the reason that file is present is because that game includes GOG Galaxy functionality which is implemented by the galaxy.dll library, and in order for the operating system to load the program that library must be present (and every other library the program uses). If the library does not exist, the operating system will give an error because it is unable to load the DLL and resolve the symbols. This is a technical requirement mandated by the design of the operating system.
It has no bearing at all on whether or not someone uses Galaxy client, nor whether they use or care about achievements or any other features implemented by Galaxy. It has nothing to do with Galaxy becoming Steam either. It is a technical requirement that is built into Windows use of dynamic libraries and every other modern operating system made in the last 20-30 years that supports dynamic linking.
It also has nothing to do with Galaxy being optional or not. You get to choose whether or not you use Galaxy client, that is your optional decision. You get to choose whether or not you care about or want to have achievements (excluding the fact that the option to disable it is not actually implemented yet because the software is not complete yet). What you do not get to optionally decide however is how the operating system or dynamic linker works. In Microsoft operating systems, Microsoft decides that, and as such libraries that a program dynamically links to must be present on the hard disk in the path of the dynamic linker so that the executable can work.
If your idea of Galaxy being optional is that you should not have any files with "galaxy" in their name on your hard disk at all then I'm afraid that you're being nitpicky out of misunderstanding how software technology works. Why anyone would be upset over the name of a very small file on their hard disk existing instead of just using and enjoying the software is beyond me.
almabrds: You don't need Galaxy to play this game.
If the dll file bothers you, you're free to remove it.
Apparently the file is there because of the achievements. A blue might give you more details, I haven't tested that yet, so I can't say for sure.
I doubt it is a sign of DRM coming to gOg.
If they do this, they will be annihilated by Steam, obliterated.
The battle would end before it even started.
Removing the DLL (or any DLL for that matter) will almost always break whatever software uses it, because the linker needs to find those files at load time. There are very few exceptions to this, such as how applications implement loadable modules/plugins/skins using DLLs for example, but regular libraries such as this need to be present or most likely the application will fail to load and the OS will rightfully spit out an error. As I mentioned in my above post, this is not DRM, it is how dynamic linking works. :)