Let my say it differently, I bought a game for 8.50 7 years ago. Not only did the game engine change, the gameplay changed completely. The game today is not worth 45
When it glitched a bunch (19 or 20) there was a visible barrier that I could not see through, walking through it will agro the zombies beyond the barrier. You can sit just outside and shoot a shotgun, you can start a campfire, as far as I can tell the only way to agro is crossing the barrier.