It is now an undisputed fact that the life form excavated from the Earth is indeed of the ancient race spoken of in legend. Furthermore, history records that these 'Ancients' channeled the power of this planet to tear the earth asunder. Using the cells of the unearthed Ancient, we have begun research on creating and mass-producing a race with comparable abilities. The primary objective of this research is to significantly reduce mako excavation costs.
The Jenova Project, also known as the Ancients Project, refers to a series of experiments performed by the Shinra Electric Power Company in Final Fantasy VII and Crisis Core -Final Fantasy VII-. Shinra conducted the experiments with the ultimate goal of creating a human hybrid with the extraterrestrial creature Jenova, whom Shinra mistakenly believed to be an Ancient. The Jenova Project's offspring become several of the key antagonists in the Compilation of Final Fantasy VII.
Thirty years before Final Fantasy VII, Shinra located the frozen remains of an alien creature inside the North Crater. Professor Gast Faremis mistakenly identified the life form as a Cetra, and named it Jenova. Seeking to monopolize Mako energy in their bid to dominate the Planet, Shinra commissioned the Jenova Project with the intent of creating a new genus of Cetra who would lead Shinra to the Promised Land said to be abundant in Mako.
The project was divided into two branches to be directed by Gast's collegues, with Professor Hojo leading Project S and Dr. Hollander leading Project G. The groups competed to produce a superior specimen, with Project S producing Sephiroth, while Project G produced Angeal Hewley and Genesis Rhapsodos.
Gast left the project and the company after discovering that Jenova is a hostile extraterrestrial life form that nearly eradicated the Cetra race thousands of years ago. Even in his absence, research continued. Using the data and results from Project S and their specimen Sephiroth, the Jenova Project entered the next phase, leading to the development of SOLDIER. Human male candidates who met the desired physical and mental qualities were injected with Jenova cells and infused with Mako energy. This boosted their physical abilities to superhuman levels, but none came close to the power Sephiroth had.
Project G's research secretly continued beneath Midgar within Deepground, where increasingly extreme and inhuman testing methods were developed to produce more varied and unstable creations compared to SOLDIER.
Objective: Implant the cells of an Ancient into a human fetus to imbue said fetus with the Ancient's abilities.
Project G's full name is "Project Gillian" for the main test subject, Gillian Hewley, though the "G" is often mistaken to stand for "Project Genesis" as Genesis Rhapsodos was the first result of the project to expose himself. Project G was run by Hollander who injected Gillian with Jenova cells with the intent that those who received her cells in turn would receive Jenova's traits. Genesis was created this way and Gillian also passed Jenova's abilities on to Angeal when she gave birth to him.
The Crisis Core Complete Guide refers to the results born out of Project G as G-Type SOLDIERs, who include Angeal and Genesis, and Hollander when he applies the same treatment to himself during Crisis Core -Final Fantasy VII-. G-Type SOLDIERs can create copies of themselves by implanting others with their cells, using Jenova's cells as a conduit to transfer the donor's abilities to the host. The host takes on the donor's appearance and gains some of their abilities. However, as the Jenova cells are not fixed in their bodies, a G-Type SOLDIER will succumb to degradation symptoms as time passes.
Though they seem normal humans, eventually the side-effects of Project G begin to manifest. Genesis, who is merely injected with Gillian's cells, slowly begins to degrade. Angeal, who is born directly from Gillian's cells, never exhibits signs of degradation, and thus is considered by Hollander to be the perfect result of Project G. Genesis can create Genesis Copies, but is only seen doing so on humans, and his copies degrade at accelerated rates. The exact rate of degradation varies depending on the subject's own physical potential.
Angeal can produce Angeal copies but unlike Genesis he does so with both animals and humans. Unlike Genesis, the transfer of abilities between donor and host can go both ways for Angeal: as he can imbue others with his abilities, he can also absorb copies he has created to take on their abilities. Even though Angeal is a successful subject, eventually his copies will begin to degrade.
Project S, code for "Project Sephiroth," was the second and arguably more successful branch of the Jenova Project. It was carried out in Nibelheim's Shinra Manor. Compared to Project G, the methods of Project S were direct: Hojo injected Jenova cells into a human fetus, the child of he and Lucrecia Crescent, a scientist also working in the mansion on her own project. Lucrecia gave birth to Sephiroth, and although Sephiroth didn't gain the abilities of an Ancient as envisioned, he was deemed a superior subject to Genesis and Angeal, and research on Project S continued into the development of SOLDIER.
The Crisis Core – Final Fantasy VII Ultimania explains Sephiroth is a superior specimen due to the nature of his exposure to Jenova cells; while Genesis was exposed to Gillian's cells which contained Jenova cells, and Angeal was born from one of Gillian's eggs after she was injected, Sephiroth was exposed to pure Jenova cells undiluted by human DNA, and thus his abilities are stronger than those of Genesis and Angeal and never shows signs of degrading. He is never shown creating copies of himself, but is able to receive and deliver abilities to others, as shown by Cloud inheriting SOLDIER abilities through his cells.
Hojo hypothesized that when Jenova's cells are separated, they will instinctively attempt to reintegrate, and human hosts carrying Jenova's cells will be compelled to gather together. Hojo had the survivors of the Nibelheim Incident, including Cloud and Zack, injected with samples of Sephiroth's cells, turning them into Sephiroth Clones. These "clones" are not direct copies in the same sense as the Genesis and Angeal copies, as they received none of Sephiroth's abilities. Due to their weakened mental integrity, pivotal for SOLDIER members to remain sane, most became mindless drones devoted to Sephiroth and prone to being telepathically controlled by him.
Cloud maintains his free will unless directly influenced by Sephiroth, whereupon he has to fight to remain in control. Zack, on the other hand, had no reaction to the experiment, possibly due to his exposure to Jenova cells as member of SOLDIER. Through Sephiroth's influence, the clones (including Cloud) are drawn to the North Crater where most are killed by Sephiroth and their Jenova cells absorbed.
Genesis is cured of his degradation by the Goddess Materia and is taken away to Deepground. Unwilling to join the organization, Genesis isolated himself in a cavern underneath Midgar. Shelke Rui of Deepground survived the organization's destruction after defecting to the WRO, and as one of the Tsviets, carries Genesis's cells. Weiss also carries Genesis's cells, but his fate is uncertain as Genesis is seen carrying his body away after awakening from his slumber. Angeal perished, and just prior to the events of Final Fantasy VII, Lazard and the final Angeal Copy follow suit, leaving the offspring of Genesis as the only known survivors of Project G and Deepground.
Following Sephiroth's death, his influence by means of the Jenova cells in the Lifestream causes the fatal disease Geostigma to infect the Planet. In Final Fantasy VII: Advent Children, the last remaining cells of Jenova are found in the Northern Cave. They are absorbed by Kadaj, shapeshifting him into a new body for Sephiroth. Cloud defeats Sephiroth, and he fades while hinting at his return, leaving Kadaj to die. This makes Cloud the only known surviving product of Project S. Cloud, Shelke, Genesis, and Weiss thus bear the last known fragments of Jenova's cells, either directly or via the cells of Genesis or Sephiroth.