Crysis is based in a fictional future where an ancient alien spacecraft has been discovered deep within the Earth. The single player campaign has the player assume the role of United States Delta Force operator Jake Dunn, referred to in-game by his fieldname- Nomad. Nomad is armed with various futuristic weapons and equipment, most notably a "Nano Muscle Suit". In Crysis, the player fights both North Korean and extraterrestrial enemies, in four different locations: a tropical island jungle, inside an "Ice Sphere" (consisting of the same jungle, but frozen), the alien ship itself (with a zero-gravity area) and an American aircraft carrier.