Firewatch is a beautiful and gripping experience. It's smartly written, with well developed characters and some of the best dialogue and voice acting I've came across in any game.
It mixes genre well, with genuinely moving moments and characters you're drawn to invest in, while keeping you consistency gripped with incredibly tense thrilleresque sections. The vast and stunning natural environment around you contributes to a feeling of eerie isolation as the game goes on, and you share your characters increasing anxiousness and paranoia when it becomes apparent that you are not alone.
Firewatch's other great success is how this all draws you to invest completely in the central mystery; and ultimately this is also where the game disappointingly falls a little flat.. From the moving and poignant introduction, through the consistent building of tension, and suspense at the unravelling of the games main mysteries, to an urgent ending as the forest fires rage and close in around you.. there comes a suspenseful expectation which is not met by the far more understated (both in tone and event) and somewhat anticlimactic ending. While in some ways I do actually like the ending in terms of those characters and the games themes, due to the build-up it inevitably makes the experience feel a little confused in tone in the end, and just a little unfulfilling.
On the whole I really enjoyed Firewatch; would recommend.