The Legend of Zelda: Twilight Princess:

Twilight Princess takes place several centuries after Ocarina of Time and Majora's Mask, and begins with a youth named Link who is working as a ranch hand in Ordon Village. One day, the village is attacked by Bulblins, who carry off the village's children with Link in pursuit before he encounters a wall of Twilight. A Shadow Beast pulls him beyond the wall into the Realm of Twilight, where he is transformed into a wolf and imprisoned. Link is soon freed by an imp-like Twilight being named Midna, who dislikes Link but agrees to help him if he obeys her unconditionally. She guides him to Princess Zelda. Zelda explains that Zant, the King of the Twilight, has stolen the light from three of the four Light Spirits and conquered Hyrule. In order to save Hyrule, Link must first restore the Light Spirits by entering the Twilight-covered areas and, as a wolf, recover the Spirits' lost light. He must do this by collecting the multiple "Tears of Light"; once all the Tears of Light are collected for one area, he restores that area's Light Spirit. As he restores them, the Light Spirits return Link to his Hylian form.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". What must Link collect?
Tears of Light