It's difficult to determine. Sometimes stories labeled as 'true' have fictional elements added for dramatic effect. We'd need more context or research to know if Rosa Island is truly based on facts.
It depends on your perspective. While it may draw inspiration from real-life situations, it likely has some fictional elements added for narrative purposes. So, it's a blend of truth and creativity.
The truthfulness of the Snake Island story is hard to determine. It could incorporate elements of truth mixed with creative elements to make it more engaging or mysterious.
Battleship Island has roots in reality. However, for the sake of storytelling and entertainment, certain aspects could have been embellished or fictionalized.
Rose Island is a true story to a certain extent. It might have been embellished or dramatized for the big screen, but the core idea and the basic events are rooted in reality.