(Long time listener, first time poster)
You should listen to this interview of Sean Vanaman and Rich Sommer by Giant Bomb's Austin Walker : http://www.giantbomb.com/podcasts/talking-firewatch-with-sean-vanaman-and-rich-somme/1600-1503/
They explicitly talk about the intro and how it came about as well of a lot of other stuff. The whole interview is great an funny. Rich Sommer seems like an incredibly cool and down to earth dude - and is also apparently a massive board game geek.