The core of the game consists of the player controlling a human assisted robot (HAR) to fight against various opponents. The basic modes of gameplay are the single player, two player or the RPGesque tournament mode. The single player mode revolves around the employees of the WAR corporation trying to gain control of the Jupiter's moon, Ganymede for their own secret agendas and the development of a mysterious project only known as Nova. The player has to select from a pool of 10 possible pilots and HAR combinations and advance through a unique storyline for each pilot by defeating rival pilots. In the two player mode a single computer is used to host two player usually dividing the keyboard into halves. OMF also supports the use of Joysticks.