While the climactic (or, for some, anti-climactic) ending of Firewatch left plenty of players happy to leave the Thorofare behind, a second playthrough could still have plenty to offer. Depending on how thorough you are, there may still be a number of interesting conversations, events and even locations that you missed on your first time around.
Warning: This post contains spoilers for the end of Firewatch, so you might want to save it for your second playthrough.
The Road In
While in my first playthrough I didn't try to return to the Thorofare Trailhead at all — Delilah never asked Henry to go back there, after all — if you do decide to make the hike back down there, you'll be in for a bit of a shock. The trail is completely blocked off by an 'impassable rock slide', and a conversation with Delilah reveals that this is indeed the only way in or out of the Two Forks area. "What is this, the Twilight Zone?" she asks. As a plus, this is one of the earliest places you can pick up Turt Reynolds/Shelley Duvall.
This little scene can be experienced either really early in the game or right near the end, but your best chance of getting it is to hike out to the power poles on Day 1 instead of going through the cave back to your tower. Most people would have found the decrepit old outhouse, but if you hike a little further along from that you'll find a burnt out old shack.
Explore the house and you'll encounter an event that you can radio Delilah about — in exchange for an interesting story about the house and its former inhabitant, 'Racoon Carter'. This won't happen on Day 2, though you will get a chance again in the last couple of days while the air is smoky. Being in the 'wrong' area generally tends to result in some new dialogue — if you radio Delilah about the utility poles on Day 1, she'll also give you the helpful tip that you are way off course.
At the end of the game, Ned lets you up to his hideout to have a bit of a rummage through his stuff and you discover that he has quite a nice view over the valley, complete with a set of home-made chimes. If you walk up to the area below his living space at any time during the game, you can't actually see his little habitat but you can hear his chimes. To check it out for yourself, head over to this spot on the map:
The Cable Car
While the game doesn't lead you to this point until the very end, you can still stumble across the emergency cable car as early as Day 2. If you ask Delilah about it, she'll tell you it's only for emergencies and that you definitely can't go for a ride in it — hinting even early on that she doesn't actually want to meet you. If you push her, you'll still get a funny little conversation for your troubles. This option doesn't seem to pop up on later days, however, such as when you hike up to the supply box to pick up your food (and only your food, hopefully).
Naming The Fire
When Delilah wakes you up to see the first fire of the summer, it turns into an oddly tender moment if her and Henry are friendly. At one point she'll ask you if you're looking at the fire, and if you're off investigating something else, Henry will answer "no, I'm not". There's another option that the game can pick up on here, however. If you turn around and look up towards Delilah's lookout, Henry will answer "no, I'm looking at you". Awwww.
While it's not quite TF2, you can actually collect and wear hats in Firewatch. If you remember to put them on, you'll get a hatted Henry in both his inadvertent selfie and in Delilah's drawing of him. There are two in the game: The first can be found in the intro sequence, on the ground next to your truck once it's parked in the Thorofare parking lot. The second can be found in an unmarked white cache box next to Hawk's Rest lookout. Henry will hang them up in his tower before he goes to sleep, so remember to put them on in the mornings if you want to be wearing one or the other.
Dave And Ron
In many of the cache boxes are letters between two rangers, Ron and Dave. While there are only six to be found in the whole game, you can tell a lot about the two characters from what they've written, and it's led to plenty of discussion. Ron seems to be a typical man's man, drinking and scoring dates with women — "someone to throw back a case with" in his own words. And Dave? Well, from the notes he sends, it's implied that Dave may be thinking of Ron in more than just a 'friendly' way. Not that Ron seems to catch on: "Debbie was tryin to explain why they'd kick your ass so good and I just don't get it."
While this one seems to be pretty central to explaining the mystery, it seems like many people (including myself) didn't actually encounter it. Once you have the wave receiver, it can potentially lead you to a dead elk with a tracking collar around its neck — the same kind of collar Ned leads you to in the end of the game. On Day 78 after finding the hideout, head north until the wave receiver picks up the signal. This little discovery helps tie up the game's mysteries a bit more cleanly, strongly implying that Wapiti Station was an elk tracking and monitoring station all along.
While it's hard to miss this drawing at the end, you may be surprised just how many different options you can end up with, depending on how you act and how you describe yourself to Delilah. If you ignore her through most of the game, she'll even draw you as a grumpy-looking hunchback. She can also doodle a couple of different things around the picture, including a picture of your turtle, and "Burt + Turt" in a love heart — if you name your turtle Turt Reynolds and also compare yourself to Burt Reynolds.
While it's not as exciting as it sounds, there is an alternate ending to Firewatch. If you wait two minutes after the chopper arrives and don't climb in, it'll fly off without Henry, leaving him in the burning forest. Whoops. While some people have said that this scene could even imply suicide on Henry's part, he could just be planning to go off and live with Ned. You never know.