Citizen Abel: Gravity Bone is a Freeware Spy Fiction First-Person Shooter by Brendon Chung, set in the nondescript South American locale of Nuevos Aires. You play Citizen Abel, a secret agent who embarks on missions that involve performing peculiar or outright bizarre actions, such as secretly feeding an insect to a man at a party, or taking covert photographs of black birds. Your actions are only ever explained at the end of a successful mission by a Motor Mouth robotic voice - and even then you never know who your "clients" are, or what their greater purpose is. Download it for Windows here.