Hello everyone. I just bought The Witcher 3 + All extensions but I'm currently in an intenrship and thus I live in a place where the internet connection is really bad.

Thing is, one of my co-workers also has the game installed (Same edition and also bought on GOG).

My question is : Can I simply copy/paste his game folder on my computer and the start a new game ? Will I still get updates and all ?

Thanks !

Yeah, that should work. But if you're not using the optional Galaxy-client (which still is in Beta), you won't "get" updates but have to download them yourself, of course. You can download patch files from your gog library.

Edit: You better copy his installation files, or the game will likely not run, because there are no entries in your machine's registry without properly installing the game.

There is no need to do it. Just copy of game's folder and then importing to GOG Galaxy. GOGY will download some files but it will be counted rather in MB not GB.

I'm moving the game in this way between my PCs because in one location I've got slow net access.