[
  {
    "type": "region_overlay",
    "regions": [ "all" ],
    "city": {
      "houses": { "wizard_tower_1": 10, "wizard_tower_2": 20 },
      "shops": { "magic_shop": 100, "used_bookstore": 225, "magic_academy": 150 }
    },
    "field_coverage": { "other": { "f_boulder_large": 0.98, "f_glow_boulder": 0.02 } }
  }
]