Everything is free on the Epic Games Store this week. Before you go wild, I should clarify that it's Everything the game, a thoroughly brilliant and meditative journey through the universe. It's joined by the considerably spookier and more violent Metro 2033: Redux.
Everything is the kind of game you've just got to let wash over you. You can embody everything in the universe, from tiny organisms to entire galaxies, all while listening to narration from philosopher Alan Watts. It's silly and whimsical, but it's also a powerfully thought-provoking sim. Check out Andy Kelly's Everything review.
At the other end of the spectrum sits Metro 2033: Redux, 4A's moody, claustrophobic shooter. I played the original 2033 and Last Light, so I've not checked out the remasters, but according to Jem Alexander's Metro 2033: Redux review it's absolutely worth playing again.
Both of them are free until October 3, when they'll be replaced by Minit.