A couple of weeks ago you could get Codemaster's Dirt Rally for free by subscribing to the Humble Store's newsletter. Now you can the 2015 racing game for free simply by downloading it from Steam before September 16.
Once you do, it's yours to keep forever.
That's hell of a deal for just clicking your mouse a few times. In our review we called it "the best rally game in years." Steam reviews—over 20,000 of them—are 87% positive, so we're not the only ones who enjoyed it. Heck, it even has full Oculus VR support. Not bad for a game that's discounted 100%.