How to play Grapple on Mac

You must stop the galactic jailbreak. The player controls a small character which can move up and down, while firing horizontally to the right. The screen is divided into 5 rows, and the player can fire high, medium, or low in each row. At the beginning of each level, 5 alien creatures attempt to escape to the left. Each monster must be shot in a specific location, and when they hit they are pushed back to the right. When a monster is pushed off the right of the screen, they are eliminated, but the empty rows can then produce small blue creatures which endanger the player. These creatures are destroyed in one hit. The player loses a life if any monster reaches the left side of the screen. Victory for each level is achieved by clearing the screen. Each level has monsters which take progressively more hits to push back, increasing the difficulty. The player starts with 3 lives, and gains an extra at 30,000 points.