This is similar to what I remember from playing Operation Flashpoint: Cold War Crisis. I wasn't very good at the actual game, but there was a post-credit sequence I would skip to where you could just walk, drive, and fly around quiet, rural, and sparsely islands. The simulation is pretty unremarkable by todays standards but being able to explore a huge open world at my own pace was incredible at the time.

One encounter that stands out in my memory was of driving along a remote road in the middle of the night and coming across a bad traffic collision where a truck had completely crushed a small car along with its driver. Something about the brutal and almost mundane nature of the encounter has stuck with me.