The object of the game is to defend your cities and missile bases. The enemy fires interplanetary ballistic missiles and cruise missiles,
both of which are aimed to destroy your cities and missile base. There are only two types of cruise missiles; smart cruise missiles, which
try to evade your anti-ballistic missiles (ABMs), and dumb cruise missiles, which fall in a straight path.
The enemy attacks in a series of waves that may vary in the number of attacking interplanetary ballistic missiles.
Each consecutive wave moves faster. The faster the wave, the more difficult it is to defend the cities. So, the faster the wave, the higher
With each wave you have 30 ABMs for defense. Your launching missile base, (bottom, centre of playfield) contains only 10
ABMs at a time. As each set of 10 ABMs is fired, you automatically receive 10 more from you underground missile dump (bottom, left corner).
Once you have fired all 30 ABMs, you are defenseless until a new wave begins.
You must protect your launching missile base from enemy fire. Once it is hit, all of its contents are destroyed. However,
you still have the remaining missiles in the underground dump. The game ends when all of the cities are destroyed.
• Mouse: movement (required)
• Left: Alpha fire
• Up/Down: Delta fire
• Right: Omega fire
• Mouse button: fire nearest base
• Interplanetary Ballistic Missiles: 25 points
• Enemy Cruise Missiles: 125 points
• Unused Antiballistic Missiles: 5 points
• Saved Cities: 100 points
• Scoring Multiplier
• Waves 1-2: 1X
• Waves 3-4: 2X
• Waves 5-6: 3X
• Waves 7-8: 4X
• Waves 9-10: 5X
• Waves 11+: 6X
Bonus cities are awarded every 10,000 points.
Once a score of 810,000 is reached, a large number of cities are awarded (150 cities plus the continuing accrual of bonus cities).
On the 255th and 256th yellow screens, known as the 0x stages, the scoring increases by 256 times the base value.