Green Star is a simple shoot-em-up released for the Commodore 64. The player controls a turret which can move left and right along the bottom of the screen and fire upwards (à la Space Invaders). The game is played against a woodland scene with grass below the turret and trees in the background. From the top of the screen aliens fall quickly towards the ground. The aliens fall at different rates and the sideways movement of the aliens varies - some move in a constant direction, others weave.
The objective is to survive each wave of aliens. Aliens crashing into the turret cause a loss of one of the player's three lives. Aliens reaching the ground do not cause the player to lose a life. Also, shooting aliens does not score any points for the player. Instead by surviving the wave, the player scores 100 points.
Each sector has a different graphical style of aliens, but the background appears to stay constant.
Written by A[ndreas]. Mettler