Probably standing out in the open and ending turn, ending turn until he runs out in the open and you see him.

We're then stuck in combat mode wondering where the bad guy is. We run around the map, in combat mode because the bad guy's after us, looking for some guy that's hiding around a corner. 3 For aviation purposes in the United Kingdom, a visibility of less than 5 km (3.1 mi) but greater than 999 m (3.278 ft) is considered more mixed if relative humidity is 95 or greater less than 95, the fog is reported. OR, we have the issue where combat mode starts and we don't know where the bad guy is. By definition, fog reduces visibility less than 1 kmwhile the fog causes less give visibility. Is that house empty? Is it full of bad guys? Should I go in prepared or not? Did I miss someone? If I walk in there, will I be shot at? Things like that can be fun, or they can be annoying. There's also the fact that I don't want to spend my time running around looking through EVERY NOOK AND CRANNY of a house just looking for characters.

Instead, you'll poke your head around, see a bad guy, combat mode will be initiated, your initiative will be too low, the bad guy will go first, and you'll be dead. To a point, it makes sense to hide characters you can't see, but just remember that you can't duck around a corner and jump back when you spot a bad guy. I can't say I'm sold on the fog of war /line of sight in RPGs.

Fallout 1 fog of war