April Ryan is a struggling student artist in the year 2209, recently arrived in the big city of Newport. Lately she has been seeing strange, life-like dreams. Somewhere in the mountains, a mysterious white dragon talks to April, calling her the "mother of the future". When April wakes up, she dismisses the vision as a nightmare. However, an old enigmatic man named Cortez, whom April has spotted near her house before, unexpectedly tells her that she must face the reality in her dreams. Soon April learns that our reality is but one facet of a universe that consists of two parallel worlds: Stark, the world of science and technology, and Arcadia, the world of magic. Though raised in Stark, April possesses the ability of shifting between the two worlds, and must restore the balance in both of them before it is too late.

The Longest Journey is a third-person puzzle-solving adventure game. The player navigates April over pre-rendered backgrounds with fixed camera angles, interacting with people and objects through a simple point-and-click interface. The gameplay follows the traditional template introduced in LucasArts adventures, relying mostly on inventory-based puzzles and multiple-choice dialogues to advance the story. To help keep track of things, the game includes a diary, where April records her thoughts about important events, and a conversation log that records the text of every conversation.

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