In a new Gamasutra feature, PhD and educator Luke McMillan -- who consults for Ubisoft -- writes that line of sight is the "primary metric that alters difficulty" in games, and explores its use in detail
McMillan writes that "this observation is in relation primarily to the FPS genre," before launching into a diagram-filled exploration of how line of sight affects players.
"The greater a player's line of sight, the more able they are to plan ahead and think strategically about the game world," he writes.
The crux of it is like this: "Greater line of sight also allows the possibilities for a larger amount of tactical options, as the player will have more time to plan and also a greater situational awareness. On the other hand, reducing the player's line of sight will result in disadvantaging the player, as they will have less situational awareness and less time to act to certain problems."
For example, McMillan suggests that a gantry in an FPS level could be seen as a portal due to the way it shifts the tactical situation -- and field of view -- for players.
"This is why we often see players taking the 'high ground' in a tactical scenario, as the height elevation allows for a greater situational awareness as opposed to if the player remained on the lower parts of the map. Windows and doorways also constitute portals within game levels."
A gantry, he writes, "will give the player strafing abilities whilst they are targeting enemies on the lower floor. The combination of these two elements combined give the player the most advantageous position in this scenario.
On the other hand, a player below the gantry, "will have a significantly occluded view of the position above them. Further to this, the only way they have of removing this occlusion is to backpedal." The consequence? "Any enemy attempting to target them will require fewer correct cycles to gain an accurate hit," McMillan writes.
While this is just one simple example, the feature is full of well-diagrammed instances
of how player field of view concretely affects play -- and thus challenge and level design. It's live now on Gamasutra.