Board Thread:Dark Souls/@comment-212.56.138.90-20160107130147/@comment-4511886-20160107184032

GFWL doesn't exist anymore. It was closed down, and DaS now uses Steamworks.

You should be able to use your copy's activation code (the one you had to write into GFWL) in Steam. This will put the game into your Steam library, and it should work just fine. Do note that you'll lose your character (GFWL save files are locked to the account for some reason, which means you can't load it without GFWL) but I honestly doubt there is any other way to make the game work at this point.

Hope it works out for you!