They upload gog installers for games. Gog (good old games) is a game storefront that doesn't have any drm, so the installers you download off this website are identical to what you'd get if you paid, cryptographicaly signed and everything. Because they don't have any drm to check if you own the game or not, they work without any modification.

Because gog has a strict no drm policy, most AAA game publishers don't put their games on gog, but there are some. The big focus is indie games though. If nothing else, I like to try before I buy.

I hope this explanation makes some sense, I am very tired.