Civilization: Call to Power (called CTP or CTP1 for short) is a PC turn-based strategy game developed by Activision (made and sold under license from Hasbro Interactive) as a successor to the extremely successful Civilization computer game by Sid Meier. It was ported to Linux by Loki Software. Apart from the isometric view (used in Civilization II but not in Civilization), one of the innovations is slavery, with a Slaver unit, slaves (cheap labor but may rebel if not properly minded), and an Abolitionist unit.