Its closer cousins are indie games like Everybody’s Gone to the Rapture (released last year), Dear Esther (2012), and perhaps most famously, Gone Home (2013)—titles referred to as “walking simulators,” a classification that initially felt mildly pejorative but has managed to stick. Minecraft, which initially prospered on the PC, was an early success story in the now-flourishing world of independent games—easily bought online and downloaded onto mass-market consoles like the Playstation 4 and Xbox One. Such games rarely cost much money or require tons of processing power, partly because they’re driven entirely by story and mood.

In Everybody’s Gone to Rapture, you play as a person exploring a small English town where everyone has mysteriously disappeared. In Dear Esther, made by the same indie studio, you wander an uninhabited island in the Scottish Hebrides, slowly learning the story of a woman who has died in a car accident. In Gone Home, you are a young woman returning to her family home, only to find it empty, prompting you to piece together the past to understand the present. Solitude is crucial to all of these games: Like most “first-person” games, you’re an unseen actor progressing through various environments to advance the story. Unlike most such games, though, in walking simulators you don’t have to shoot any soldiers or fight any monsters along the way.

Such games would have been unimaginable even 10 years ago, when the quality of writing and voice acting in the medium was rudimentary at best. One reason Firewatch works so well is the astonishing naturalism of its dialogue, which powers the game as you wander through its beautifully designed world (created in part by the Internet-renowned Olly Moss). The game’s story is driven by conversations you have over your walkie-talkie with your fellow lookout Delilah. Your chats start out as gently funny, move into deeper, more heartfelt territory, and then lurch into Lynchian terror as you begin to realize all is not as it seems.

The voice work is done by Rich Sommer (of Mad Men fame) and the veteran video-game actress Cissy Jones, and Moss’s painterly visuals are at once comforting and suspiciously beautiful. When things start to go awry, the tranquility of the environment starts to seem threatening without anything actually changing. Most walking simulators lean heavily on the details of their environment, but Firewatch is particularly successful in using its design to move along its overarching story (which I won’t spoil in any detail).

But more than anything, Firewatch is a game that explores the state of being alone, both psychologically and physically. You hang on your walkie-talkie conversations with Delilah, mostly small talk and technical information, because staving off silence feels so important. Most games these days have radars, complex heads-up displays, and arrows pointing to your next objective on the screen at all times; in Firewatch all you can do is mark up a paper map in your pocket that you need to take out and look at every time you want to get your bearings. Because of details like these, there’s a sense of accomplishment to every step you take.