The Global Defense Initiative relies on well-armoured and powerful, but slow units. They take conventional technologies and upgrade them to increase firepower and efficiency. However, they lack a long-range unit in the early game.
Infantry
Minigunner
Cost: $100 | Prerequisites: none
Equipped with the GAU-3 “Eliminator” 5.56mm chaingun, this trooper deals reasonable damage to enemy infantry and is commonly used for early game scouting. Unless massed, Minigunners are hardly useful for anything else.
Grenadier
Cost: $160 | Prerequisites: none
The Grenadier is faster, farther-seeing, and harder-hitting than normal infantry. The grenade this unit throws can not only go over walls, but can destroy them as well. Their grenades deal splash damage in a small radius and suppress nearby infantry.
Rocket Soldier
Cost: $300 | Prerequisites: none
These infantry units are slower and easier to kill than other infantry, but can deal more damage to armour than any other infantry unit. Their major advantage is the ability to attack airborne units, and are most effective as a support unit in diverse groups.
Engineer
Cost: $500 | Prerequisites: none
Engineers are used to capture enemy buildings or repair friendly ones. Since they carry no weapons, they are extremely vulnerable on the battlefield and must be directed very carefully. Engineers are very slow, so loading them into an APC is an ideal way to move them about the battlefield.
Commando
Cost: $1000 | Prerequisites: Advanced Communications Center
The Commando uses a Raptor 50cal. assault rifle with suppressor that is able to take out infantry units from afar. In addition, he carries C4 explosives which level structures instantly when placed.
Vehicles
Harvester
Cost: $1400 | Prerequisites: Tiberium Refinery
This armour-plated vehicle seeks out and scoops up raw Tiberium, then transports it to a Refinery for processing. It is slow and unwieldy and will need to be protected. However, it is well-armoured and can take a beating until reinforcements arrive, and can crush infantry if the need arises.
Light Scout (Humvee)
Cost: $400 | Prerequisites: none
These all-terrain attack vehicles are fast and effective against infantry. Its light armour makes it vulnerable to any explosive weapon.
Armoured Personnel Carrier (APC)
Cost: $700 | Prerequisites: none (legacy balance); Repair Facility (modern balance)
The APC transports and protects up to five infantry units heading to and from battle locations. Its heavy armour, fast speed, and long sight range make it an ideal scouting unit. It is also useful for crushing infantry.
Medium Tank
Cost: $800 | Prerequisites: none
From its single barrel, the Medium Tank fires armour-piercing shells. It is faster, heavier and more destructive than Nod’s Light Tank. It is effective against both vehicles and structures, but can be taken down by groups of infantry or aerial units.
X-66 Mammoth Tank
Cost: $1500 | Prerequisites: Repair Facility
Armed with dual 120mm cannons and Mammoth Tusk missiles, this giant is a force to be reckoned with. These weapons help compensate for its lack of speed, and enable it to take on just about any target on land or in the air. When this unit takes a lot of damage, it can slowly regenerate its health back up to 50%.
Rocket Launcher (a.k.a. Multiple Launch Rocket System – MLRS)
Cost: $800 | Prerequisites: Advanced Communications Center
GDI’s artillery fires 227mm rockets and is effective against just about everything, including aerial threats. With no short-range fighting ability, this unit needs close-quarter backup.
Mobile Construction Vehicle (MCV)
Cost: $5000 | Prerequisites: Advanced Communications Center
As you will see in the section on GDI buildings, the heart of every base is the Construction Yard. When deployed, this vehicle becomes a Construction Yard, providing you with all of the benefits of that building. To deploy an MCV, select the vehicle and hold the cursor over it. If the cursor changes to a white circle with four arrows, left-clicking on it will deploy the vehicle. If the cursor has a red circle with a line through it, there is either not enough room to deploy or something is in the way. Move the vehicle (or the offending object) to find a suitable deployment site. The MCV must be protected at all costs.
Aircraft
Transport Helicopter (Chinook)
Cost: $1500 | Prerequisites: none
Provides field transportation for up to 5 infantry units, rapidly deploying them into or out of battle. This unit is basically an aerial version of the APC without the weapon.
Orca
Cost: $1200 | Prerequisites: none
This vertical take-off and landing (VTOL) craft carries five salvoes of TOW rockets that are exceptionally useful for taking out enemy armour. When an Orca runs out of rockets, it must return to a Helipad for reloading.
Support Aircraft (A-10 Warthog)
Unbuildable
These units are highly manoeuvrable, ground-hugging craft that level enemy units with napalm as part of the Airstrike support power. Since the A-10 bombs in a line, it is a good idea to pick a target that is part of a group.
Ships
Hovercraft (campaign only)
Unbuildable
This heavily-armoured unit deploys men and vehicles during amphibious assaults.
Gunboat (campaign only)
Unbuildable
Heavily armoured, and armed with surface-to-surface missiles, this unit is the backbone of GDI’s naval forces, and is used for beach bombardments. In all of its ingame appearances, it is only able to move from west to east and back.