Superweapon (Tiberium)

The concept of a "Weapon of Mass Destruction" has been around for quite some time; however, only in the twentieth century did military technology progress to the point that weapons capable of instantly killing large groups of enemy personnel with little risk to the wielder get developed.

Great World War II
During the Great World War II, the Soviet Union developed the first true weapon of mass destruction; the atomic bomb. Although it's blast yield was small compared to similar fission devices built later, the weapons were considered an extreme threat to the Allied Forces. Fortunately, Vladimir Kosygin, the scientist responsible for these weapons, realized that Stalin would not hesitate to slaughter innocent civilians with them, and defected. With his knowledge, the Allies successfully destroyed Dark Horseman, the base at which the weapons were being constructed. Fuel air bombs and Migs that drop nukes are other classified reports of WMDs.

Both sides also researched other so called "superweapons", which had a utility purpose. Using designs from Nikola Tesla, the Soviet Union developed the Iron Curtain, a device that would render a unit or structure temporarily invulnerable to attack. The Allied scientist Albert Einstein developed the Chronosphere, a unique machine that, by warping time and space, could instantaneously move a unit across great distances. However, problems with these devices led to their abandonment.

First Tiberium War
By 1995, GDI discreetly developed the Ion cannon, an orbiting satellite weapon that could be used as an unstoppable surgical weapon. Kane was thought to be dead when GDI forces used their on cannon on the Temple of Nod in Sarajevo.

Meanwhile, Nod forces had managed to procure large amounts of fissile material, and the scientific expertise required to effectively use them. Nod Temples served as an ICBM launch facility.

Second Tiberium War
GDI upgraded and expanded the Ion Cannon network, although it functionally remained similar to the older surgical strike.

Nod largely abandoned it's nuclear arsennal, choosing to use the airburst Multi missile, which would fragment into many smaller bomblets in midair. Also, Nod invented the Chemical missile, which utilized the processed roots of the Veinhole monster, and would release deadly Tiberium Gas upon striking a target.

One superweapon that Nod invented, but never used, was the World Altering Missile. Kane intended to use it to mutate all carbon-based life worldwide into tiberian life, but the missile was scrapped prior to launch by Michael McNeil.

Third Tiberium War
GDI's Ion cannons received a significant update by the time 2047. Now capable of large scale destruction, GDI relied heavily upon the threat of death from the skies to keep Nod in check. This overreliance nearly proved fatal, however, when after the destruction of Goddard Space Center, the Ion Cannons were temporarily offline, and Nod began a global offensive.

Nod had once again began to stockpile nuclear weaponry, once again launched from the Temple of Nod. The nuclear missile that destroyed the GDSS Philadelphia was launched from a concealed base in Cairo. Though GDI managed to confiscate these stockpiles following the conquest of Egypt, Nod stole GDI nuclear warheads in the Australian Outback. They also got Tiberium Vapor Bombs and Catalyst missiles for the scrin.

Nod also developed the Liquid Tiberium Bomb, a weapon that had a minimal blast yield several hundred times greater than that of a nuclear warhead. Worse, it would cause a chain reaction with any Tiberium in the blast radius, increasing the power greatly. GDI accidentally set off this device when the Ion Cannon was used during the Siege of Temple Prime.

The Scrin were attracted to Earth by the Liquid Tiberium bomb, and brought along their own superweapon, the Rift Generator. It alter the fabric of time and space, creating a singularity in a targeted area. In non-technical terms, anything in the radius of destruction would be sucked into an artificial, temporary black hole. The Scrin Mothership also appeared to be a superweapon, it's powerful Catalyst cannon being able to destroy anything unlucky enough to be underneath the Mothership.