Vaesen aren't simply monsters to destroy. They have their own lives, dreams, motivations, and problems. Some cooperate with humans, others are mischievous or murderous - but they always have reasons for their actions. You might discover a vaesen harming people because humans destroyed its home, or that a 'victim' actually made a deal with the creature. Moral ambiguity makes the game richer and forces you to consider consequences of your choices.
The countryside is alien and threatening compared to civilization. Cities are where you feel safe. Remote villages, dark forests, and mountainous wilderness represent the unknown. Anything can happen away from civilization - no one will find you if you go missing. This creates natural tension: when you venture into nature, you're leaving safety behind. The environment itself becomes an antagonist.
The 19th century brings industrialization, railways, factories, and social upheaval. Old traditions are dying. Nobles lose power to wealthy merchants. Rural people flee to cities. This changing world confuses the vaesen and creates opportunities for them to cause chaos. Many mysteries tie into this theme - the clash between old and new, tradition and progress, creates supernatural crises.