Gone Home is one of the 60+ titles in the Humble Monthly Trove, a bank of games that are available to all Humble Monthly subscribers. Occasionally, one of these games gets given away free for a limited time, and Gone Home's number has been called—you can download it here until May 5.
You'll need to login to your Humble Bundle account first, but after that you'll get a DRM-free copy of the game, meaning you'll be able to launch it directly from your desktop rather than going through a launcher.
In Gone Home, you explore a detailed house to learn about the lives of the people that lived there. It's more than five years old, but it's still worth playing because of its touching story: you can read our review from the time here.