There’s an intimacy to running a custom route at two in the morning. The passengers are textures and scripted behaviors, but in your head they are real: tired workers clutch briefcases, students with backpacks that glow under streetlights, an old man who always stumbles on the first step and is steadied by the same driver in every iteration. You begin to invent their lives—why the route matters to them, what the city sounds like in their memories—and the simulation blooms. Modders build not only vehicles but tiny theaters for these characters, full of offhand details: a flickering stop sign, a puddle that reflects neon, a stray cat that becomes a silent recurring motif. Those details are what separate a good mod from a living one.