As the enemy's raids grow more and more intense, you may feel the need to spend some of your valuable supplies on erecting ground defenses to shield your gun emplacment from paratroopers that manage to evade your anti-aircraft fire and reach the ground. You can purchase 4 types of defensive weapons, and can also purchase 4 types of improvements to make them more durable. Once you purchase defensive weapons and improvements, they will engage enemy ground troops advancing toward your position, firing automatically as targets move within range. Watch out for troopers landing inside your defensive perimeter!
Two sets of defenses can be purchased, one to the left of your gun, and the other to the right. Each defense emplacement has a pair of status bars beneath it, indicating the current level of ammunition and defensive value. When ammunition is exhausted, the effectiveness of the defenses at stopping the enemy ground troops will understandably be lessened, although the enemy's rather limited tactical sense will lead them to destroy the emplacement before continuing on to your gun. When an emplacement's defense value drops to zero, it is destroyed and must be replaced.
Speed Shot reduces the amount of time required to reload your gun and fire another round. You activate it on a shot-by-shot basis by holding down the Option key. While the Option key is depressed, a yellow lightingbolt appears at the top of the screen to the right of the gun icons. A counter displays the number of Speed Shots remaining. When you fire your gun with Speed Shot activated, the reload time for the next shot is reduced.
Extra Ammo Capacity
Cost: 6000 per 10% increase
This improvement increases the amount of ammunition storage for all of your anti-aircraft and ground defense weaponry by 10%. While expensive, Ammo Cap can prove valuable on later raids when those extra Hypersonic missiles or Flamethrower fuel can mean the difference between life and extinction.
Camouflage Netting
Cost: 12000 per net
Getting tired of all those engineers dropping demolition charges on your gun and ground defenses? Sick of seeing those expensive flamethrowers destroyed without having a chance to fire? Maybe camouflage netting is the answer. These nets disguise the appearance of your emplacements, making it difficult for the nearsighted engineers to spot them from the air. They're pricey, but can be worth the cost on later raids when the engineers are coming thick and furious. The 'L' and 'R' nets protect your left and right ground defenses respectively, while the 'C' net protects your central AAA gun. Ground defense netting is destroyed when the defense emplacement is destroyed. Netting on your gun can be destroyed by accumulated damage to your gun over several raids, so watch out.