Here are the exact story lines submitted by blizzard on the dates of the Starcraft release. The story is devided by the choosen races.
They are pretty long, but for those that it intrests... here you go. It's actualy pretty intresting!
Terran
The Earth, the Terran homeworld, is corrupted by the political forces, internal wars, the overpopulation and the contamination. The new technologies, the clonation, mutation and the cibernetics implants were totally rejected by those defenders of the humanity that disagree with these technologies and they took to the humanity to a chaos generalized in a battered and super populated Earth. So a new organization is founded, the UPL(United Powers League) that will take charge putting order to the desperate situation. The UPL carried out a big purification on Earth, by killing all those persons whom were considered dangerous for the humanity, the oppressive regime of the UDL keep under control, for now, the Earth.
During a series of experiments made with prisoners, a scientist, Doran Routhe, planed to send ships with humans in them in cryo-hybernation status, asleep. The ships took off and headed towards a far away planet to colonize, but a series of damages avoid to the ships to reach this objective. Anyway, the ships voyaged in the space for decadates, until, without more energy each one landed on differents planets. The first ship successfully landed on Umoja, the other ship on Moria and the last one on the Tarsonis planet. The humans that where asleep on the ships, woke up from their long rest and prospered in those planets, they reproduced, colonized other planets, they discovered new technologies, etc, but separate each one of them, each one in their planet.
Due to the new technologies, such as the warp gate speed, the groups of humans discovered themselves. The forces of Tarsonis, the biggest, formed a Confederation, The Terran Confederates. Many conflicts and wars started to happen between them.
Then, Khoral, one of the best and greatest colonies of The Confederates, rebelled and begun a big conflict. The war lasted a little, since The Confederates decided to nuke all the planet with nuclear bombs. The result was disastrous. Almost all form of life on the planet had been exterminated.
Arcturus Mengsk ,to revenge and combat against the Confederates, formed a terrorist revolutionary group known as Sons of Khoral. The group soon acquired fame for its revolts, but it also acquired a bad reputation diffused by The Confederates.
In the middle of the war, an alien fleet, The Protoss, invaded and attacked the Chau Sara´s colonies, destroying everything. Uncannily, after the attacks, the alien force retreated, but little time later another alien force, the Zerg, invaded the Terran Colonies. The Terran, weakened by the internal war and conflicts between them, couldn´t hold the invasion.
The Terran campaing
Here is where the Terran campaign starts. You, with Raynor and Mengsk must hold Zerg invasion. Jim Raynor joined to Mengsk in the Sons of Khoral to fight against the alien invasions and The Confederates. Sarah Kerrigan, second on command of the Sons of Khoral will help you in the duty. This girl has a dark past, she was victim of illegal experiments and mutations with the Zerg, then Mengsk rescued her from the hands of the evil Confederates´scientists. But later she is captured by the Zerg, so then she becomes Infested Kerrigan.
During the course of the Campaign, you´ll see the two faces of Mengks, according to him, The Zerg are a tool of The Confederates to exterminate them, because the Psi Emitters manufactured by The Confederates were able to attract the Zerg, with psi signals.
The Terran Brood War Campaing
In the Brood War Terran campaign, now you direct the UED (United Earth Directorate), under the orders of Admiral Dugalle and the Vice Admiral Stukov, whom has came from Earth to conquer the Mengk´s Territories, his empire, and to control the Zerg. They conquered Khoral, the Mengk´s empire,without too much trouble, with his empire destroyed, Mengsk is forces to escape from Khoral.
During the course of the Campaign, a new character, Duran, shows up. This mysterious character discourages the Admiral to destroy the Psi Disruptier. Such artefact was able to interrupt the Zerg psi signals and control the swarm. Stukov realizes of what Duran was doing and fortunately could avoid Duran to destroy the Psi Disrupter, but later Stukov is killed by Duran, with the approval and under the orders of the Admiral, his own friend. With the Psi Disrupter under its power, the UED captures and neutralizes The Overmind and colonizes Char.
Protoss
The Protoss were created by the ancient race Xel´Naga,though we don´t know much of this race, it´s said that it was a very advanced race that governed thousands of world around the universe, also, it is said that they were a peaceful and benign race.
The Xel´Naga wanted to create a pure race, the perfect form of life. They carried out many experiments with differents races, but without success, the races they made were very primitive and they didn´t reach the perfect form of life as they wanted. Then, the concentrated their efforts on Aiur, a huge jungle world, where one of their creations where developing favorably, this race seemed to be superior to the other races they created before. The Xel´Naga called this race the First born, or The Protoss. The Protoss, with their dexterity and an incredible adaptation to the most extreme conditions of life, were without doubts , what the Xel´Naga were looking for. But what more surprised them were the Protoss ability to comunicate themselves with a powerful telepathic system.
The Protoss lived in harmony, with the care of their creators, whom were watching them wihout their warning. However, the Xel´Naga were not pleased with their creation, they thought the Protoss were developing very slowly, for that reason they decided to accelerate the evolution process, this caused an incredible physical and mental develop, the Protoss begun to progress quicker than ever. Finally, the Xel´Naga showed themselves to their creations. The Protoss adored them as gods. Nevertheless, the acceleration of the evolution progress of the Protoss and the integration of the Xel´Naga culture into the Protoss changed them, they were not the same, and according to their creators the Protoss had lost the essence that made them the perfect race. The Xel´Naga, disappointed, abandoned their creations for ever, convinced that they were not the perfect form of life. The Protoss, seeing that their creators were abandoning them, infuriated attacked the ships of their their creators while they were escaping. The Xel´Naga broken-hearted, repeled the Protoss attack and escaped to the infinity of the space. The Protoss overturned their fury against themselves. A big conflict escalated among the differents tribes, called the The Eon of the conflict. The war lasted many generations, and it is known as the lost period of the Protos´s story.
But one day, a mystic Protoss, called Khas, discovered the Khaydarin Crystals, antique instruments of the Xel´Naga. Khas was able of channel the energy of those crystals, so he had access to the psychic union that all the Protoss share. This telepathic union is present in all the Protoss, but it was forgotten, that was the forgotten essence. Khas understood that the war didn´t have fundament, and he begun to reunited and taught to the youngest Protoss how to use their psychic union. The psychic union among all the Protoss reunited them, and marked the end of the war, the Protoss reunited and mated through their psychic union. Finally the war ended and the Protoss started to rebuild their homeworld. The Protoss suffered a radical change with this event, a new type of administration was created, the Khala. The Protoss society was divided in three castes, The Judicators caste, the Templars caste, and the Khalai caste. The Judicators caste is integrated by the oldest members of the society, who take charge of the administration and order of the Protoss people. The Templar caste is formed by the Protoss warriors, and the Khalai caste, which is the most of the Protoss society, is formed by workers, engineers, scientists, etc.
The Conclave, a group of senior and experimented Protoss Judicators, were in charge of make the decisions of any kind and to lead, order and watch the order castes. The Khala was successful and the Protoss prospered quickly. The Protoss expanded to other worlds, and as their creators, the Protoss watched and protected the inferior races that were living under their shadow.
But not all was successful in the Khala, some tribes, known as the Rouge Tribes, flatly refused to join to the other tribes, and to accept the Khala laws. Therefore the Conclave ordered to the Templars to exterminate these rebeles tribes. Adun, a Protoss warrior, was in charge of the mission. Adun refused to kill his own brethren. He tried to convince them to join to the Khala, but he couldn´t make it. So he tried to hide the tribe from the eyes of the Conclave. But the Rouge tribe, without the Khala´s law to discipline them, soon developed a powerful psychic power, that caused big energie storms on Aiur that attracted the attention of the Conclave, and they were discoverd. The Conclave, seeing that the Templars didn´t exterminate the Rogue Tribe as it was ordered, decided to expel the rebels tribes from Aiur, the tribes were loaded in an old but still functional Xel´Naga´s ship and throwed to the deep space.Later on, those tribes were called The Dark Templar.
The Protoss soon met with the Terrans. The Protoss found the Terrans an interesting race that, in spite of the internal conflicts among the differents colonies,they prosper and advance faster,but the Protoss just watched them from a prudent distance,far away of their conflicts,as their creators did with them.
One day,Tassadar and his expedition fleet were wandering around the Terrans worlds until they found Aliens organisms, the Zerg. This organisms were studied by the Protoss and surprisingly the discovered that this bugs were compatible with the Khaydarin crystals´s energy, actually, they could channel those energies. So the Protoss understood that the Zerg were another race created by the Xel´Naga. The Protoss knew this race could be extremely dangerous.
The Zerg invaded the Terran's world infesting and consuming everything to their step, Tassadar was sent to the infested sectors and ordered to halt the Zerg invasion in the Terrans´ worlds. The Conclave ordered him to burn the infested humans worlds, Tassadar knew this would kill everything form of life in the planet´s surface, including the Terrans. Tassadar disobeyed the Conclave´s orders and tried to save the Terrans of the Zerg than killing them with the Zerg.
The Protoss campaing
In that moment is when the Protoss campaign begins. Tasssadar is considered a traitor and is replaced by you, you are the new Executor. The Overmind has located the location of the secret homeworld of the Protoss, Aiur, and invades it successfully, later on the own Overmind set up on Aiur. Now your duty as Executor is to hold the Zerg invasion and to protect your people. Fenix, a Praetor, will help in the duty, Judicator Aldaris, as representative of the Conclave will be your boss. While you fight on Aiur, Tassadar, who has been considered as a traitor to the Conclave, is attracted by the cosmic energies that the Kerrigan´s chrysalis has emitted when it was incubating, on Char.There met with Raynor and Zeratul, a Dark Templar. Tassadar learned a lot about the Zerg, he learned that the Overmind controls the swarms through Cerebrates. Tassadar also discovered that the psychic powers of the Dark Templars are the unique thing that can definitively kill the Overmind and the Cerebrates, avoiding them to reincarnate. Therefore, disobeying the orders of the Conclave, that order him to return to Aiur, Tassadar undertakes the search of the Dark Templar Prelate, Zeratul, to save the entire race, and you will help him. Aldaris informs to the Conclave of your treason, Tassadar and Zeratul are considered traitors and the Conclave orders to capture them so they will be executed. You shall prevent that this happens.
Finally the Conclave is defeated by the Zerg. Tassadar, Zeratul, and Raynor must now aniquilate the Overmind. In the final episode, Tassadar directs his Ship, The Ganithor (A Carrier) into a collison course with the Overmind, with the objective of aniquilate it for ever. Tassadar achieved to channel the Dark Templar´s enegies on the Ganithor and successfully destroyed the Overmind, but, as is predictable, he died in that sacrifice.
The Protsss Brood War campaing
In the Brood War Protoss campaign, with Aldaris as an ally again,and with Zeratul and the new Praetor, Artanis you shall leave the desolated world of Aiur and escape to Shakuras, the secret homeworld of the Dark Templar. Unfortunately, Shakuras is invaded by the Zerg too. The Matriarch of the Dark Templar, Razagal, decides to use the powers of an Ancient Xel´Naga temple, that can channel the powerful energies of the Uraj and Khalis crystals. You shall go and begin the search of this crystals,but in that moment Kerrigan shows up and warns to the Protoss that a new Overmind is growing on Char. Aldaris believes that Kerrigan is lying, but the Matriach Razagal trusts in what Kerrigan says. Now you will work with her.What Kerrigan wants is that the Dark Templar kill the new Overmind, but this will happen later. Aldaris, who believed that it was wrong to ally with Kerrigan, rebels against the Matriach, Zeratul and Artanis intervene but then Kerrigan appears and kills Aldaris. Now is when they realize of the deceit. In spite of everything, The Protoss could join the crystals in the Xel´Naga temple, a big explosion is produced and finally, Shakuras is free of Zergs, at least for now.
Zerg
The Zerg, like the Protoss, were created by the Xel´Naga, that were looking for the perfect form of life. After the failure with the Protoss, the Xel´Naga didn´t lose the hope of create their perfect form of live. They found another world, Char, where they´ll create the Zerg. The Xel´Naga developed the small insects that lived on Char in a supreme race, the Zerg.The Zerg evolved quickly, their method to evolve was to absorb and assimilate to the inferior races, incorporating their genetic qualities. Only the purest and most useful races were absorbed, those who were considered insignificant or threatening races were eradicated. The Zerg continued assimilating races, and they were doing it so quick that a heap of mutations was taking place in their bodies, they made much more stronger, more corpulent, their bodies were covered by spines and they were armed with powerful claws. The Xel´Naga worried about this, they begin to think the Zerg were running without any control, remembering how they failed with the Protoss, The Xel´Naga decided to do something. They created an Agent capable to reason, feel and think collectively, like every Zerg,that were able to govern and lead the swarm:The Overmind.
The Overmind, a creature capable to feel what every Zerg felt. The Overmind soon became a clever creature, and indispensable creature for the Zerg.The Overmind created Cerebrates, similar creatures to the own Overmind, whom will be his Agents. The Cerebrates aid the Overmind to control the hive. Each Cerebrate had a different task, besides, every Cerebrate had its own swarm, that were controled by him. In turn, The Cerebrates control the swarms with Overlords and Queens. The Zerg creatures are unable to disobey the orders given my Overlords and Queens, and in turn these can´t disobey the orders of the Cerebrates,and these the orders of the Overmind. This effective organization system allowed the Zerg to develop and to prosper quickly. The Zerg had become a pure race, the Xel´Naga knew that they had achieved their objective.
But the Overmind was very strong, it had cut its psychic links with the Xel´Naga. The Overmind was warned of the big Xel´Naga´s ships over his planet, then he ordered to his overwhelming swarms to destroy the Xel´Naga´s ships,to their own creators. That was the end of the Xel´Naga,they just couldn´t hold the Zerg invasion and were annihilated in the hands of their own creations.A part of them were absorbed by the Zerg,so in that moment the Overmind knew who were and all their secrets. The Overmind assimilated the Xel´Naga´s power and information and became stronger and sager. The Overmind had access to the Xel´Naga´s most guarded secrets and discovered the existence of a powerful race in the space confines, the Protoss. The Overmind determined that he must find the Protoss and absorb them. The swarms left the ashes of Char and caused havocs in everyt world that they settled while they search the Protoss. The Overmind knew and respected the immense psychic power of the Protoss, and was looking for a way to overcome such powers. In his seach for more races to absorb, the Overmind found the Terrans, the Terran was a weak and fragile race, but they´re developing a psychic power,like the Protoss. The Overmind knew that the Terran would be what he needed to overcome the Protoss´ psychic power, though the psychic power of the Terrans were still in infant stages, the Overmind knew that in a few generations the Terrans would develop a powerful psychic power. For that reason the Overmind ordered to his swarms to invade and absorb the humans. The Overmind schemed an infestation plan of the Terrans´ world to take them. The plan was running fine until a Protoss fleet(leaded by Tassadar) arrives to the infested Terrans´worlds and begins to fight against the Zerg. The Overmind, marveled by the incredible power of the Protoss, allow to this Protoss fleet to destroy his forces so he can learn more about the Protoss.The Overmind, astonished by the Protoss power, abandons the initial infestation plan and prepares a strategy to annihilate the Protoss.
The Zerg campaing
The Zerg campaign starts when a new Cerebrate born,that Cerebrate is you. The Overmind orders you to take charge of the protection of a creature that he has captured,A Terran Ghost, Sarah Kerrigan. The Overmind captured Sarah Kerrigan because he knew about the enormous psychic power that Kerrigan had.Kerrigan begun his transformation, protected by a chrysalis, Sarah Kerrigan will become Infested Kerrigan, a terrible agent of the Overmind. During their gestation in the chrysalis, Kerrigan emitted psychic waves that reached the confines of the space. This waves attracted the attention of Tassadar, Zeratul and Raynor toward the chrysalis. You shall protect Kerrigan until she is ready to reborn,and then escort her in her missions.
The psychic energies of the Dark Templar are different to the energies emitted by the normal Protoss´units, these energies are very similar to the energy of the own Overmind. Zeratul, knowing that these enegies could be useful against the Zerg, arrives to Char and murders Zasz, one of the Overmind´s Cerebrates.Normally, if a Cerebrate is killed the Overmind has the option of reincarnating it, but the psychic energies of the Dark Templar Zeratul avoided the Overmind to reincarnate to Zasz and caused harm to the Overmind too. However, When Zeratul killed Zasz, the mind of the Zeratul and the Overmind touched, the Overmind took out from the Zeratul´s mind the location of the secret Protoss homeworld, Aiur. The search for Aiur has finished. The Overmind successfully invaded Aiur, transfered there and disseminated the terror in it. Aiur suffered a grand devastation.
The Zerg Brood War campaing
Now, In the Brood War Zerg Campaign you are a servant of Infested Kerrigan, The Overmind has died in the hands of the Protoss. Kerrigan, now with nobody to control her can do what she wants. Infested Duran will be with you to serve Kerrigan. The first thing you must do is to destroy the Psi Disrupter, this artefact is avoiding Kerrigan to control her minions. To catch some Zerg forces to destroy the Psi Disrupter, Kerrigan bids to Mengsk some Psi emitters. These emitters are capable to attract the attention of nearer Zergs. In return Kerrigan commits to aid Mengsk to retake Khoral from the hands of the UED. Kerrigan,b esides Mengsk, has the support of Raynor and Fenix, whom will suffer the consequences by allying with Kerrigan later. Anyway, The Psi Disrupter is destroyed and Kerrigan helps Mengsk to retake Khoral, not only for the deal with Mengsk, but also because the UED´s forces on Khoral were a threat to Kerrigan´s plans. Besides,The UED control The Overmind (the new Overmind),which provides some control over a few Zerg swarms, the UED didn´t doubt to send the Zerg to attack Kerrigan,but Kerrigan could defeat these Zerg forces. Then Kerrigan sends you to kill his allies, Duke and Fenix. After this, Kerrigan must kill the Overmind(so the UED doesn´t have control over Zerg forces), and since the only way to definitively kill the Overmind is using Dark Templar´s energies, Kerrigan kidnaps to the Matriarch, Raszagal, so she can attract the attention of Zeratul, and forces him to kill the Overmind. After killing the Overmind, Zeratul retrieves the Matriach and attempts to escape from Kerrigan. Kerrigan sends you to avoid this and Zeratul, fearing that the Matriach is infested, Zeratul is forced to kill her. Kerrigan, as an act of kindness, let Zeratul to escape. Without the Overmind, the UED no longer has control over the Zerg and it´s weakened, Kerrigan assures of exterminating the remaining UED´s fleets, and the Admiral Dugalle is forced to commit suicide. Kerrigan has achieved all her objectives, her goals, she´s annihilated all her enemies, she is the Queen of the Zerg. Meanwhile, the Protoss will return to Aiur and will try to reconstruct their ruined homeworld.