Probably easiest to uninstall, keep the saved games, then reinstall in the new location and copy the game saves across.

You can't often get away with just dragging and dropping to a new location because, when the game installs, it writes files elsewhere and creates registry entries and so on that will refer to the original install path and won't be updated when you move it.

When a game gets installed in a certain place, it "registers" itself with the PC to that area. Every other operation that depends on that data will look for it in that place. That's why you can't just copy/paste most games around and expect them to work.

Think of it like moving from one state to another and telling absolutely no one. A lot of people and mail will be looking for you in the wrong place and be rather puzzled as to why you are not there, hence they won't "function".

I understand what you guys are saying. But then why does this not happen in some specific games like WoW? It IS as easy as copy/paste, it's launcher automatically detects it and continues doing the auto update etc.

Anyway it's extremely stupid if I have to redownload the entire 30 or whatever GB of content just to change directory. I live in a sort of third world country called turkey and we have limited downloads here (even for the most expensive subscriptions that are labelled as "limitless" for these c*nts limitless means around 200 GB)..

OK I've solved this. I'll explain to anyone else who would like to know this. Here's what I did.

- I copy/pasted the entire folder to the new directory.
- Changed the Witcher 3 folder name in the old directory to Witcher3.backup (just in case). At this point GoG won't be able to see the game anymore, the "play" button will be grayed out.
- On GoG galaxy, click the "+" sign, select install from library. I forgot whether it asks to chose the install dir. Before doing this, I went to settings and changed "Intall game to" the new directory that I want the games moved to, so you should probably do that as well.
- There will be some "checking" and some quick installation and it's done.

Thank you, it worked!

There is actually a low level file-system option to do just this, it´s a bit more complicated than just drag&dropping directories though. But not really. :)

It´s a NTFS in-built feature called "junction".
You basically drag&drop move your game wherever the heck you want, then using the "junction" functionality to make the system think the game is still back where you installed it.
To your system a junction looks like a normal directory, but it´s infact pointing to the new place you moved your game.

You can look up guides explainig this more indepth and even get a comand line tool.
Or you can install this handy ap that simply integrates the functionality into your explorer drag&drop/right-click options.
http://schinagl.priv.at/nt/hardlinkshellext/hardlinkshellext.html
Scroll a bit down to the Junction instruction and read just those.
The rest is a bit too confusing for now and not really what you need to do anyway.

tl;dr install ap, find moved game, right-click directory, make junction at old place(either holding ctrl & right mouse buttan or right-click menue options [link source]->[paste as junction]), system hax0rd