Fly along and blast away all of the baddies, trying not to let them shoot your or fly into you. The things that makes this horizontal shooter different from the thousands of other horizontal shooters out there are:

• Although the game perpetually continues to scrolls to the right, you can fly your ship in any direction on the screen as you go.
• The alien space ships do not follow any set flight pattern and, in some levels, which particular alien ship chosen to appear on the screen is random (like in the first level, “Nasties”).
• The alien ships also employ avoidance techniques to your gun blasts. Along with weapon fire, you can destroy the enemy ships with your rocket flame; you just have to get close enough to them to do so.

The game has six stages (or acts, if you will): “Nasties”, “Bombers”, “Cibolians”, “Asteroids”, “Invaders”, and “Moonbase”. After the completion of the six stages, you move up a level and start again. However, as the levels increase, so does the difficulty of each stage. The aliens on each stage have their unique abilities and forms of attack, which kind of forces you to change your tactics in each stage of the game.

Use the joystick to fly in all directions and press to fire you weapons. You can set the number of players (one or two) by pressing 1 or 2 on the title screen.