The Vanishing of Ethan Carter Redux had Steam trading card support added on March 30, 2016. There are 6 cards in the series, and you'll receive 3 cards at random for purchasing and playing the game.
This is an enhanced version of The Vanishing of Ethan Carter, which also has Steam trading cards. Purchasing the original version also gives you this one, but they are separate applications in your Steam library. Only running the 'Redux' version of the game will give cards from this series - the other application gives cards from the The Vanishing of Ethan Carter card series.