GOG Galaxy, the client that's a little bit like Steam, has entered open beta for all to try.
This is the optional, carefully-does-it next step for the download games store, bringing the community and their game collections together.
GOG Galaxy introduces multiplayer and matchmaking, social features like friends lists, plus stat tracking, achievements and all that stuff. There's cross-play with Steam as well, so you're not in an 'either or' situation.
It works offline, and you can tinker with the various options you don't automatically want on. Games don't have to automatically update, for instance.
Remember, this is a beta - it's not quite finished, and it's also likely to evolve over time too. Head to the GOG Galaxy site to join in.