Density
Also said as Negative space, Content density, Breathing room
How much there is to do in a given stretch of ground, and how much empty ground lies between. The emptiness is negative space, and like the gap between notes in music, it is doing a job.
Too thin, and the player is walking and bored. Too thick, and nothing stands out, because every marker is competing with the next. Quiet stretches are what make the next discovery feel like one.
Say it
“The map has an icon every 20 seconds and players are numb to them. Cut them by half and leave a full minute of quiet riding before each major site.”
Where you’ve seen it
Shadow of the Colossus has a vast land with almost nothing in it but its sixteen colossi, and the long empty rides between them are what makes each one feel enormous.
Not to be confused with size
Size is how much ground there is. Density is how much happens on it. A small map can be sparse and a huge one can be cramped.