GOG

GOG.com is a digital distribution platform with a carefully curated catalog of games, a "you buy it, you own it" concept and a genuine concern for its clients. GOG, formerly known as Good 'Ol Games, is one of the leading DRM-free game distributors. This means you become the sole owner of all games you purchase and no longer need to log in to the GOG client to play them.

Another thing to note about GOG is that it offers deep discounts on games that were launched only one or two months before. If you don't believe it, just go to the GOG homepage and you'll see discounts ranging from 20% to 90% off recent titles.

Detailed information:

Number of titles: 4,000+
Platforms: Windows, MacOS, Linux

Website: gog.com