"Armada" is a science fiction novel by Ernest Cline that follows the story of Zack Lightman, a high school student and avid gamer. He spends his days immersed in video games, particularly in a space combat simulation called "Armada." One day, Zack sees a drone that closely resembles one from his favorite game, prompting him to realize that the line between his virtual reality and the real world might be blurring.
As the narrative progresses, Zack discovers that the game is not just a simulation but part of a government initiative to prepare for an impending alien invasion. He is recruited into a secret military operation that uses his gaming skills to fight against extraterrestrial forces. Zack struggles with the weight of responsibility as he transitions from player to a key defender of Earth.