There's a neat shift that happens when you look past the obvious demon gates and hunter stuff in 'Solo Leveling'. Setting a big chunk of the action on Jeju Island wasn't just about a cool location. It reframed the entire power structure of that world from a national, almost corporate endeavor into a desperate, almost mythic siege. The island stopped being a tourist destination and became this isolated, hostile territory that even the strongest hunters couldn't tame.
What I find really clever is how it flips the script on dungeon crawling. Usually, it's about clearing a contained space and leaving. But on Jeju, the 'dungeon' is the entire landscape, spilling out constantly. The S-rank hunters aren't just raiding a boss room; they're trying to reclaim land from an entrenched, living army. It turns the fantasy into a war of attrition, which feels way more consequential than another portal in a subway station. That sense of a lost frontier really changes the stakes.
It also forced the worldbuilding to consider logistics and scale in a way the early arcs didn't. How do you supply a siege? What happens when the military fails and it's just hunters? The island setting made those questions unavoidable, grounding the high fantasy in a grim, practical reality.