Throughout the play sessions, Hocking provided a sort of real time director's commentary, pointing out items of interest or explaining an event. He recommends lighting a building on fire to force the soldiers out into the open telling us, "That's the way we play and I think the systems in the game are going to encourage people to play that way as well."
The notion that the entire game is simulation based begins to creep out after watching three other writers play through the entire demo. I'd leave and come back an hour later to see if another batch of writers followed the same paths I'd already seen or did something different. While each playthrough, including my own, included objectives like destroying a radio tower and making it to the hang-glider (yeah, there's a hang-glider and a whole lotta open plains), how you accomplish those objectives is a relatively open-ended affair.
Fire is a big part of the game and one of your main tools; you can use it to burn down a field of grass, a row of trees, or even entire buildings. Once the flora is burnt down, it will begin to grow back and even display different stages of growth.
If you "die" in the game, one of your AI friends will come to the rescue and drag you off to safety. It's an entirely immersive effect, with your character blinking in and out of consciousness. You have no control until you get mended, and then you slowly stumble back to life. When asked if friendly AI can ride shotgun in your Jeep, Hocking admitted they didn't design it, and they're "certainly not going to add it" but he wouldn't be surprised if it didn't happen occasionally. Again, it's simulation based.
All 50 square kilometers aren't open to you immediately. After the first 30 minutes to an hour, you'll unlock the side missions which immediately grant you access to approximately 25 square kilometers of the game's map. You'll need to play through about 1/3 to 1/2 of the game's missions to unlock the entire thing, which includes three towns (two "main ones") and seemingly dozens of set pieces from remote outposts to radio towers to mining operations.