As an update to the GOG.com 10th anniversary celebrations, it turns out that Shadow Warrior 2 won the public vote to decide which game was to be available not only DRM-free but also monetarily-free. Accordingly, you can now head over to this page and avail yourself of a full copy at no charge for another ~40 hours as of the time of this posting.

Shadow Warrior 2 is a first-person shooter that released a little under two years ago to the day, and now has two free pieces of downloadable content as well (The Way of the Wang, and Bounty Hunt Part 1). It has a very positive rating on Steam, and elsewhere, and costs $39.99 currently. It goes without saying then that if this is a game that interests you, you should definitely pick it up for free on GOG while the offer lasts.