Command & Conquer 3: Tiberium Wars/Turtling

A turtling strategy is to build massive defenses around your base rather than spending money creating units. Building defenses costs less than creating units to defense the base, but the defenses cannot be moved to different location so artillery units, which outrange defenses, are deadly against them.

Some players underestimate the importance of defenses, thinking that defense of their base can be carried out by units which can move but having a solid, static defense wall around your base gives a player a much safer home to strike forth from. A good defensive wall is also very useful if the terrain gives your base some protection as less defense structures are needed to protect your base. It is a good idea to have some rapid moving units to deal with any enemy long-range units that come in to attack your defenses.

GDI
GDI's anti-aircraft defenses are its weak point so many AA Batteries will be needed to be effective. In Kane's Wrath this deficiency has been taken care of with the introduction of the Slingshot AA unit and the Tungsten AA Shells upgrade. All GDI defensive turrets have stealth detection capabilities.


 * Watchtower is GDI's anti-infantry defense. Its twin machine gun doesn't do much damage although in Kane's Wrath the AP Ammo upgrade significantly increases the amount of damage. As the Watchtower targets individual infantry in a unit, lone Watchtowers can have trouble dealing with infantry swarms so they are best employed in small batteries of 2 or 3.


 * Guardian Cannon is GDI's anti-armour defense. It is slow-firing but deals moderate damage so again is best employed in small batteries of 2 or 3. In Kane's Wrath the Railgun upgrade significantly increases its damage and makes this structure much more effective against vehicles as well as infantry. The ZOCOM faction lacks the Railgun upgrade so for more advanced anti-armour structures, ZOCOM players will have to wait until the Sonic Emitter is available.


 * AA Battery is GDI's anti-aircraft defense. The AA Battery is GDI's weakest defensive structure and must be employed in large numbers to be effective against more advanced or fast-moving enemy aircraft. In Kane's Wrath the Tungsten AA Shells upgrade significantly increases the damage dealt by these structures.


 * Sonic Emitter is GDI's advanced anti-armour defense. Its sonic waves can strike several targets along its line of fire meaning it is good against massed waves of vehicles. It is also reasonably good in the anti-infantry role with the same firing characteristics. These are best placed at the end of routes that enemy units are known to be using to attack your base or within the ground control established by Surveyor/Outposts to defend a Tiberium field.


 * Rig is a mobile unit capable of deploying into a Battle Base. In this mode is sports twin Guardian Cannons which GDI and Steel Talon players can upgrade to Railguns and a AA missile launcher. It's most useful ability in Battle Base mode is the deployment of repair drones meaning is can repair nearby vehicles. The Rig is best used as a support vehicle with a mobile strike force, combines with a few Slingshots it can move with the strike force and deploy behind them when they meet the enemy to provide a quick repair point to keep units in the fight.

Nod
Nod's defenses are in good balance with each other and they are cost-effective. In Kane's Wrath there are several upgrades for defense turrets: Quad Turrets (adds an turret to the hub), Charged/Supercharged Particle Beams (increasing damage from Shredder Turrets), Tiberium Core Missiles (increasing damage from SAM Turrets).


 * Shredder Turret is Nod's anti-infantry defense. The 3 (later 4) turrets means that the Shredder Turret is better at dealing with massed infantry assaults than GDI's Watchtower as it can target 3 or 4 soldiers at once. It is also possible (should you have the time or can be bothered) to manually aim each turret.


 * Laser Turret is Nod's anti-armour defense. Again due to the multiple turret nature of this structure, multiple units can be engaged. Again, these turrets can be individually aimed.


 * SAM Turret is Nod's anti-aircraft defense. The same characteristics as the above turrets apply here.


 * Obelisk of Light is Nod's advanced anti-armour defense. Its power output and rate of fire can be increased by having nearby Beam Cannon laser artillery units use their Charge Defenses ability.

Scrin

 * Buzzer Hive: Basically, a structure capable of sending out waves of Buzzers to shred enemy infantry. The spawned Buzzers can not be controlled, they are considered as a way to shoot and not as a unit. Good in its right, but does almost no damage to vehicles.


 * Plasma Cannon: A solid unadvanced anti-tank defense hurling out plasma disks similar to Seeker ones, the only difference being not firing at aircraft.


 * Plasma Missile Battery: An anti-air defensive structure with a medium range, medium damage and medium rate-of-fire.


 * Ion Storm Generator (Ion Column): An advanced defensive structure, the only one in the game which is at least moderately effective against infantry that has large squads, and aircraft. The column spawns an ion storm near itself, killing basically everything with lightnings.