Procedure to decrypt and backup GamersGate Game Setup Files:
The installer contact's their servers to unencrypt the installer setup.exe file. I already have all of my GamersGate installers backed up using the following procedure (and you should do it too for any games your worried about losing access to). Which basically removes the need for the installer to contact GamersGate at all, making it a normal unencrypted game installer, taking GamersGate completely out of the equation. You are only backing up the installer files, not installing the game. So this directly answers the question by the poster above.
1. Download installer to an empty directory (preferably already named for the game you are downloading).
2. It should launch into the games setup after downloading. Do not close it, but don't start installing either.
3. Navigate to folder where downloader was stored.
4. You will see the downloader file, and a folder with a random number like "435678", that is the folder where the setup files are stored and currently unencrypted (because the installer is open).
5. Copy all of the contents of the random number folder: example "435678" to the root game folder (where you downloaded the original single .exe file to start downloading the game installation files).
6. After that copy is complete, close the game's setup. It will ask to delete or keep the games setup files, select delete (this will delete the random number folder. Now delete the .exe file (always named for the game your downloading) that downloads the setup files and your done.
7. Done. Some games did come with a serial that will be present of the game's page on your "digital shelf" (look on the right just below the game's profile/avatar pic). Be sure to copy it to a text file in the root game installer folder.
If I didn't explain this well, here's another guide (on GOG of all places):
http://www.gog.com/forum/general/he...ndentify_binary_changes_in_the_launch_f/post1