You direct an onscreen cursor through the use of the trackball. You can fire any one of three missile silos using the three buttons next to the trackball. Each missile silo is stocked at the start of the round with 10 missile. The two silos on the side fire missiles off more slowly than the center silo. When missiles drop out of the sky. You must position the cursor underneath them and fire an antiballistic missile (ABM) so that their incendiary explosion destroys the falling missiles. If a missile manages to reach the ground, it will destroy any city at the location, or destroy the remaining stock of missiles in a silo.
Enemy craft such as airplanes and satellites will occasionally fly by and deposit additional missiles on the screen. Smart bombs are capable of escaping the incendiary explosions of your ABMs to a degree and must be targeted more directly. Cities are rebuilt every 10,000 or 12,000 points that you collect. The game is over when you lose all six cities.
Controls
- Trackball: Use the trackball to direct the onscreen cursor. The cursor indicates the position in space where you would like your ABM's to explode, and hopefully burn up a missile or smart bomb. You can rolls the cursor to any position on screen above the landscape and below the score.
- ABM Fire: You are in control of three missile silos, Alpha, Delta and Omega. Each silo contains 10 missiles per stage. When the cursor is in the correct position, press the button that corresponds to the silo that you want to fire at the cursor.
- 1-2 Players: Press either button to begin a one or two player game.
Elements
Defense System
Your city defense system consists of the on screen cursor and the three missile silos, one on the right, one on the left, and one in the center. In order to engage the defense system, you must position the cursor in space where you would like one of your 30 antiballistic missiles to explode, and press the launch button for one of the three bases. A missile will fire out of the chosen silo and explode where the cursor was positioned. Note that any object that collides with the original explosion will form a secondary explosion. It is possible for an explosion chain like this to occur over multiple generation. The two side bases launch AMBs at a slower speed than the center base, so you must plan further ahead when launching missiles from either side. If any of your missile silos are stuck by an enemy missile or smart bomb, the remaining stock of missiles for that stage are destroyed, and the silo is rendered useless until the next stage. You receive bonus points for ever missile you have remaining at the end of the stage.
Cities
These are the objects of defense that you are commissioned to protect. There are six cities in total, three on either side of the center missile silo. If one enemy missile or smart bomb manages to strike a city, that city will be wiped out. When all six cities are destroyed, your game is over. You receive bonus points for every city that is still standing at the end of each stage. For every 10,000 points that you accumulate (by default, changeable by operator), one destroyed city will be rebuilt when a stage is completed. Even if the last city was destroyed, if you reach the next point level, you will earn the bonus city and begin the next round with just one city to defend.
Missiles & Smart Bombs
This is the threat that you must contantly defend the cities below from. Every stage starts off with a hailstorm of enemy missiles. While they are deadly to the citizens of the cities below, one fact helps you defeat them: they never deviate from their path. Other missiles may, however, splinter off from a missile on it's way down. In addition to missiles, smart bombs begin to fall from the sky starting at level 6. Smart bombs are deadlier than missiles in that they can deviate from their path if they sense an explosion nearby. In order to hit them, you must fire an ABM so that it explodes right on top of a smart bomb, or squeeze them in between two explosions.
Bombers & Satellites
Bombers and Satellites begin to appear after the first stage. The fly across at a mid level altitude, and deposit more missiles into the air as they move along. You can destroy them with your missiles, and if you destroy them early enough, you will prevent them from adding more missiles that you will have to deal with. Since each stage has a set number of missiles, if you destroy the bomber or the satellite before they deploy their missiles, you will likely see their missiles added to the down pour, or more missiles will splinter apart from an existing missile.