Posted September 20, 2014
Coming back to your question - I'd break it down into few parts
First, some of the Galaxy features were available in closed multiplayer beta of The Witcher Adventure Game (networking & backend, matchmaking, lobbies, in-game chat). FYI, we've sent over 150.000 beta keys as of today and while we will be soon concluding this beta, there will be many more Galaxy-powered games like that coming, one of them in the very coming weeks ramping up into many more in the months after (way over 40 devs have access to our SDK but here we're depending on developer release schedule).
Then there is also a Galaxy Client - some parts of it, like auto-updating, were already available in mentioned The Witcher Adventure Game, and the full app supporting entire library is also coming but keep in mind this is not a small task - all our games are being rebuild to offer installation and updating via Client while also keeping their standalone installers, which creation we'd like to automate as well rather than making the whole pipeline an overkill. Then, many other features - like achievements for example - also depend on having Galaxy powered game that supports them in the first place. And as you'd expect different games then require different features.
Finally - many other features which will be later needed to power other stuff are actually already released on GOG - good example here are Galaxy accounts system, which all of you are now using... maybe some of you noticed this when we've launched new login and signup forums. It sounds like no big deal but there are many dependencies here - friends system is just one example which is also linked to achievements somewhat, which might require some overlay which in turn depends on a Client.