Forest Survival: 99 Days is an immersive survival game set in a mysterious forest where players must endure 99 nights against various threats. As the protagonist awakens without memories or tools, the primary goal is to build a shelter, craft necessary tools, hunt for food, and survive the challenges that each night brings. The game features an open forest environment with hidden paths, ancient ruins, and dark secrets waiting to be uncovered.

Players can engage in crafting and building to create shelters, weapons, and traps that will aid in their survival. The game includes a dynamic day-night cycle, where players must prepare during the day and fend off dangers at night, including randomized encounters and ghost stories. With the option to upgrade their camp and unlock lore through journal entries, players must navigate the forest's mysteries while managing the risk of losing everything in a single life.