For the Linux GOG Downloader there is now an (unofficial) Debian Wheezy and Jessie Repository.

Just add to your /etc/apt/sources.list the following Line (or create a new file in /etc/apt/sources.list.d with the following line):

deb http://mash-systeme.de/debian/ wheezy main (for the Debian 7 Wheezy packages)

OR