Keep in mind that, as has become the norm, there is a limited amount of time after "purchasing" the free game where you must redeem it on Steam.
The redemption deadline is September 23rd, 2017 at 10:00 AM Pacific. You have 15 days left!
Immediately after 10AM Pacific on September 23rd, the Steam key will magically vanish as if it were just a figment of your imagination, leaving this cryptic message behind in its wake.