How to play Rimrunner on Mac

An insectoid race travels the galaxy and colonizes uninhabited and long dead planets. Force shields were created to protect their planets from the constant attacks of the arachnoids. The force shield generators need regular recharging, a task for which a group of elite insectoid warriors was created. Riding their reptilian mounts (Runners) they patrol the colonies, recharging the generators and destroying any hostile lifeforms that have penetrated the shield. Players have to guide one of these warriors through horizontally scrolling levels, shooting at hostile lifeforms and seeking out shield generators that need recharging. A radar at the top of the screen shows the players position, as well as the position and status of the shield generators. Green generators are stable, flashing generators are unstable and red generators need to be recharged. Enemy attacks deplete the warriors health and might knock him of his Runner. On foot, the warrior is much slower and can't walk very far (the levels stop scrolling), but it is necessary to dismount the Runner to be able to recharge the generators.