The player is left a voice message by their Uncle Mortimer, an eccentric inventor and theme park owner, who has invited them to manage his theme park Thrillville after becoming enamored by the player's roller coaster designs. As the player successfully manages the park, they are assigned new parks to oversee to compete with and fend off sabotage from Uncle Mortimer's new rival, billionaire Vernon Garrison, who has entered the theme-park market with his brand Globo-Joy.