Command & Conquer: Tiberian Sun is a 1999 real-time strategy video game developed by Westwood Studios, published by Electronic Arts, and released exclusively for Windows in August 1999.

The main story of the game focuses on a second war between the UN-backed Global Defense Initiative (GDI) and the cult-like Brotherhood of Nod, both seeking to rule over an Earth which is undergoing rapid ecological collapse.

The dark atmosphere, foreboding soundtrack, and slow paced gameplay of Tiberian Sun received a mixed reception from fans upon release, although have earned it a cult following since.

Tiberian Sun takes place within an alternate timeline involving two factions - the Global Defense Initiative (GDI), and the Brotherhood of Nod - and an alien substance called "Tiberium", and occurs after the events of Command & Conquer.

Tiberium has become a serious problem for the world since its arrival in the 1990s, not only in causing a conflict between GDI and Nod over control of the valuable crystals it creates from leeching precious metals from the soil - leading to the First Tiberium War - but also allowing the substance to slowly spread and terraform the planet's ecology and landscape, including causing mutations in humans, the formation of new alien lifeforms, and the development of new weather patterns called Ion Storms.

By the 21st century, GDI is focused on researching the means to combat Tiberium's spread, making use of an orbital space station called the Philadelphia to command its forces, while Nod has splintered following the presumed death of its leader Kane, with both factions working to develop new technology to provide each with equal strength in their armies, including armoured walkers, cyborgs, advanced defensive measures, and armoured infantry.

The campaigns of Tiberian Sun focus on a new global conflict erupting in 2030, when Kane returns and re-energises Nod, forcing GDI to combat their efforts, and resulting in the Second Tiberium War.

GDI's campaign focuses on the efforts of a commander who must combat the sudden surge of attacks, working alongside a faction of mutants known as "The Forgotten", in order to thwart Kane's latest plans with Tiberium.

GDI commander Michael McNeil is recalled from a training exercise to assist in combating Nod, after being informed by his superior, General James Solomon (player character in the first game), that Kane has returned.

Eventually, GDI moves towards Egypt to combat Nod at their main base in Cairo, only to learn that Kane's ultimate plan is to launch an ICBM missile containing a warhead of pure, concentrated Tiberium, that can transform the entire planet.

Pleased with Slavik's work, Kane assigns him to disrupt a GDI excavation at Nod's former temple in Sarajevo, in order to prevent them locating an alien database and a special project housing it.

Forced to North America to retrieve it, Slavik and his crew recover the missing project and the database (the Tacitus), but are tricked by GDI into attacking a research facility, leading to them being captured.

Imprisoned in a base in Northern Europe, Slavik receives a message from CABAL that a Nod strike force has arrived to rescue him, and executes a plan that leads to his escape.

After Virgin Interactive Entertainment was facing financial difficulties and was selling some of its assets, Electronic Arts acquired Westwood Studios in 1998 and published Tiberian Sun, and had no direct part in its development.

This resulted in a number of engine and gameplay features being omitted from the game, some of which were later included in the Firestorm expansion pack, as well as numerous bugs which have not been fixed even after the patching period.

Tiberian Sun features a futuristic and ambient soundtrack by Jarrid Mendelson and Frank Klepacki, who composed the signature themes for the movie sequences, as well as the game's musical score with the intention to differ from the original Command & Conquer in order to capture the mood for each mission.

Several months after the Second Tiberium War has concluded, GDI conducts a salvage operation to recover important technology from Kane's former Temple in Cairo, including the alien database known as the Tacitus.

Because of a communication blackout with the space station Philadelphia, GDI officer General Paul Cortez assumes temporary command from a ground base, and assigns a commander to recover the database and any survivors at the crash site, whereupon the core is sent to a GDI research team led by Cortez's ex-wife Dr. Gabriella Boudreau, who is working to find the means to counter the spread of Tiberium before the planet becomes too toxic for humans to live on.

GDI, seeking another way to translate the Tacitus with Tratos dead, acquires a core belonging to CABAL in order to use the AI, and soon learn the database is missing a segment.

Boudreau eventually manages to unlock the Tacitus and acquires a vast amount of data, allowing Cortez to provide good news to the rest of GDI command as the communication blackout ends.

After securing the Tacitus, CABAL goes rogue and attempts to conquer the world through the systematic assimilation of human populations into cyborg armies, forcing GDI and Nod to unite temporarily against it.

[13] Within eight days of release, it received a "Platinum" award from the Verband der Unterhaltungssoftware Deutschland (VUD),[14] indicating sales of at least 200,000 units across Germany, Austria and Switzerland.

[31] Despite some of the game's technical issues, many reviewers considered the interactive environment, new graphics, new array of units, new concepts, single-player (story wise) and the popular multi-player to be the significant high-points of Tiberian Sun, and credited it with high rankings.