GOG Galaxy 

Check out a client for the GOG gaming service. Work with the options to browse the online store and purchase titles or download them for free. Explore various discounts, special offers, and additional information about classic games and new releases, find friends and contacts, etc.

GOG GALAXY gives you access to all the games in your computer; you can install and launch any PC game you own, no matter the platform. It combines multiple libraries into one and lets you connect with your friends across all gaming platforms, including consoles. You can keep track of all achievements earned by you and your friends, hours played, and games owned across platforms.