Overdose is a psychological horror adventure game about a teen protagonist waking up in a hospital and trying to piece together a series of awful occurrences. The game encourages mystery and plot development. Conflict and action are replaced by exploration, conversation, and environmental narrative. The characters' pasts and life-changing experiences are revealed as they go on.
New gamers are left with many questions unanswered. The story begins in the hospital and goes to places and experiences that blur memory. The overall picture slowly unravels through bizarre experiences, muddled memories, and scary facts. The mystery deepens with each new clue.
Progress involves socialisation and detail. Gamers spend their time:
These activities bring the story parts together and guide the participants to the truth.
Overdose doesn't use standard levels. As missions are completed and clues found, story sections pop up. Each contributes to the mystique of the protagonist. Story development, not character enhancements or combat successes, measures progress.

Overdose is based on mystery and story development. It focuses on exploration, communication, and environmental storytelling rather than combat or action mechanics. As the players advance, they learn about the character’s backstory and life-changing incident.