Very decent price for both the base game and the OST. If you already have one and not the other, here's the individual links:
Firewatch Original Soundtrack: $2.72, was $8.50
Firewatch is a single-player first-person mystery set in the Wyoming wilderness.
The year is 1989. You are a man named Henry who has retreated from his messy life to work as a fire lookout in the Wyoming wilderness. Perched high atop a mountain, it’s your job to look for smoke and keep the wilderness safe. An especially hot, dry summer has everyone on edge. Your supervisor Delilah is available to you at all times over a small, handheld radio—your only contact with the world you've left behind. But when something strange draws you out of your lookout tower and into the forest, you’ll explore a wild and unknown environment, facing questions and making choices that can build or destroy the only meaningful relationship you have.
The Firewatch Original Sountrack by Chris Remo features a half hour of original music including the song Ol' Shoshone, written by Sean Vanaman. Remastered for standalone release by Chris.
This is "just" a "walking simulator", but I constantly recommend it to people, because it's just so atmospheric.