[...]when we say "unique games downloaded," that means redownloading games that you have already downloaded before won't increment the counter.
[...]When the counter on the main page of the website hits 6 million, two exciting things will hapen. First off, the lucky user who downloaded our 6 millionth unique game will receive everything that's currently in the catalog, abslutely free! Secondly, everyone who has an account on GOG.com will be able to download Broken Sword: Shadow of The Templars Director’s Cut for free, thanks to Sir Charles Cecil and Revolution Software. The offer will be valid only for 48 hours starting from hitting the milestone [...]