itch.io - An online game marketplace and community.
GOG.com - DRM-free game store, selling both new and old titles. No clients required.
Origin - Origin is your new digital playground. It’s where you go to find the best that EA has to offer.
GOG Galaxy - Truly gamer friendly, DRM-free online gaming platform.
Oneplay - Buy and Rent PC &MAC games
Humble Bundle - Buy a bundle of games, you decide the price, and support charity in the process.