Turrets:
Sentry Gun and its variations and customization upgrades. Best used in the frontlines to trim down the enemy numbers. Since these are machines, they are not attacked by the Zombies - which in return make them really reliable in the battlefield as they do not die like regular recruits.
Sentry Gun
(unlocks the Sentry Gun Turret)
Turret-Based Automatic Gun
Advantages: High rate of fire, fully automatic, controllable. Will not be attacked by Zombies and does not shoot at crawlers. The sentry guns use laser beams to define the line of fire. Once the beam is crossed, the gun immediately starts shooting. Its rotation (line of sight) can be set manually.
Double Sentry Gun
(unlocks a Sentry Gun Variation)
Automatic gun with basic damage increased to 300.
Auto Aiming
(Sentry Gun upgrade)
A passive “technology” upgrade to the sentry gun that needs to be purchased still on the actual missions. New motion sensors are attached to upgraded units that can detect moving Zombies in proximity and aim gun at them automatically. Sensors are not cheap so each gun needs to be upgraded manually on the battlefield.
Speed x2
(Sentry Gun upgrade)
New improved motors will increase the rotation of the Sentry Gun (when aiming) 2 times.
Damage +50%
(Sentry Gun upgrade)
Improved barrel construction for the Sentry gun and the Double Sentry gun. Damage increases by 50%.
Damage +100%
(Sentry Gun upgrade)
Explosive ammo for the Sentry gun and the Double Sentry gun. Damage increases by 100%.
Piercing
(Sentry Gun upgrade)
Sentry Gun receives piercing ammo. It damages all targets in line of fire with single shot.