A steampunk war rages across a fictional setting, all of it secretly engineered by one man aboard a ship called the Stranger — someone who has used a powerful medallion to instigate conflicts throughout history, including World War II. Players choose from four characters — Sinnosuke, Ruby, Isha, and Stuck — each with a distinct storyline, or team up in two-character co-op mode for a combined narrative. Every run ends one of two ways: in the bad ending, the player sacrifices themselves in a kamikaze strike that destroys the medallion; in the good ending, they find a way to stop it and survive.