Is Dark Darker free?

Excuse me, I came across the game Dark Darker and it looks quite intriguing. I was wondering, is the game available for free to play, or do I need to purchase it in order to access the full experience? I'm a bit hesitant to commit to a purchase without knowing the pricing structure upfront. Could you please clarify if Dark Darker is a free-to-play game or if there are any costs associated with playing it? Thank you for your time.