A machine code arcade game in which you must destroy as many aliens as possible before they get you.
You can select one of three colours for the background. If you do not start a game immediately the program will go into demonstration mode.
Your ship is positioned at the bottom of the screen. It can move left and right and fire missiles.
Aliens appear from left and right in small groups and move into formation at the top of the screen. They dive towards your ship. Some drop bombs while they move into formation. You can destroy them at any time. When you have destroyed several waves you play the challenge stage for bonus points, in which the aliens cannot fire back and don't move into formation. The aliens come in several varieties and colours, and points are awarded depending on who you hit and what they are doing.
The instructions are included on an insert and explain the game sufficiently. The program loaded with no problems. II is a thoroughly enjoyable game with very good graphics.