I've passed this thread on to a person that's actually responsible for the Galaxy client and am hoping for a reply soon. In the meantime:

- the client is FULLY optional - you won't have to use it
- Galaxy will give you some extra functionalities (auto update, online multiplayer) and to use those, it will have to be installed and running
- the thing that installs as the client, from what I understand, is just the functionality that lets a game connect to Galaxy (if you install it). It's kind of like having a USB port in your laptop when you don't have a USB device, it ain't gonna do nothin' til you hook it up right.
- finally, right now, the Galaxy Client still in alpha/beta versions - so if you're testing, things might get buggy.

[edit] I see a more in-depth post appeared :) it explains the issue more thoroughly!

I'd like to take a moment to clear up the situation. Yes, there are few games on GOG.com (The Witcher Adventure Game, Alien vs. Predator and now Double Dragon) that come bundled with our Galaxy Launcher application.

The reason behind this decision is that those two games use Galaxy multiplayer, and for it to work we need to provide a companion application to handle user authentication and auto-updating.

Eventually, those responsibilities will be handled by the Galaxy Client, which will be a separate, standalone and OPTIONAL application.

Once the Client is released, game installers will not bundle any additional launchers or other applications.

So the current situation (a launcher app bundled with your game installer) is only temporary, as we didn't want to provide the launcher as a separate download.

If you don't plan to play in multiplayer mode you can uninstall the launcher app and launch the game directly (the launcher is also optional, but it comes bundled with the game installer).

As mentioned earlier in this topic (and in the following post) you will be able to download the standalone game installers and extras from your Library via Galaxy Client.