The best indie games like Firewatch are What Remains of Edith Finch, Gone Home and Oxenfree. Below are 8, each with the reason it is here — and, at the end, what filtering to indie costs you.
Filtering to indie means you want the answer a small team would give. It is usually the most interesting filter on this site, because small studios take the risks large ones cannot.
What you get: One strong idea, explored completely, at a price that makes trying it easy. Indies have no production to hide behind, so the design is exposed.
What made Firewatch worth playing in the first place is covered on the full list. This page is the indie part of that answer, and only the indie part.
The best short narrative game there is, and every chapter reinvents itself.
The other defining game of the genre, told through a house.
Two-way conversation as the core mechanic, with real chemistry between the characters.
Slow, strange, and beautifully written.
A forest, a mystery, and a very strong sense of place.
Wandering a landscape with no combat and time to look at it.
By people from the Firewatch and Gone Home teams, and short.
Wordless, but the same intent — connection and landscape.
Polish and scale, sometimes. A few of these are rough at the edges, and a big-budget pick will always look better doing the same thing.
Specifically, these are strong answers for Firewatch that are not indie games, so they are not on this page:
The full list is on games like Firewatch — 9 picks, no genre filter.
What Remains of Edith Finch. The best short narrative game there is, and every chapter reinvents itself.
No. Firewatch released on the PC & Modern Multi-Platform, but a recommendation is only useful if you can play it, so the picks above span platforms and eras. What they share is the genre and the reason.
Self-published, or published without a large publisher's money. It says nothing about the size of the game, which is why a forty-hour metroidvania and a two-hour art piece sit under the same label.
Constraint. Without a budget to hide behind, one idea has to carry the whole thing — and a small team can commit to something risky that a large one would sand down.
By hand. Each pick was written for the full Firewatch list first, on what the game actually does, and this page is the part of that list that is indie — never a genre tag lookup, which is how "best racing games like Super Mario 64" used to be a page on this site.
Or read the indie guide for where to start in the genre generally.