According to their own blog, Firewatch have officially received a release date. The game will come to PC and is a console exclusive for PS4. Firewatch was one of the new games showcased during. The gameplay trailer didn't show. The game seems to be built on a story where you talk over a radio most of the game, and that's how the story unfolds.
The release date is set for February 9th 2016. On the blog they shared some details that they are still optimizing the game. Their goal is to release on all platforms worldwide at the same time.
Here is the official trailer from E3: