Gameplay features exploration of environments through a linear narrative, while battles use turn-based combat with the player characters fighting both on foot and piloting large mecha dubbed A.G.W.S.

Set far in the future when humanity has left Earth, the plot follows Shion Uzuki, an employee of Vector Industries; and KOS-MOS, a battle android designed to fight the hostile alien Gnosis.

Forced to escape a Gnosis attack and head for the planet of Second Miltia, Shion and KOS-MOS are pulled into a fight between the Galaxy Federation and the hostile U-TIC Organization.

With others who join them as they head to safety, they face a deeper mystery surrounding U-TIC's goals and the plans of the immortal Albedo Piazzolla.

Xenosaga Episode I is a role-playing video game; the player controls a party of characters, navigating them through a variety of environments tied to the progression of the story.

Exploring environments, the party can collect a variety of items, some of which can be used in gameplay to boost a character's statistics or restore health.

Both player and some enemy party members also have a "Boost" meter, which when full allows that character to perform an additional action while taking away an opponent's turn.

In the year "20XX", the Zohar—an artifact dating from the beginning of the universe which connects to the realm of a god-like energy dubbed U-DO—was unearthed by an archeological expedition in Kenya; the Zohar is key to enabling humanity to travel in space beyond the Solar System.

Over 4000 years in the future, humanity has left Earth behind to colonize the galaxy following a terrible event, resulting in Earth's location being lost and the planet being dubbed "Lost Jerusalem": by the game's events, humanity has adopted a new calendar system dubbed "Transcend Christ" (T.C.

A key episode in the game's backstory is the Miltian Conflict, a war between U-TIC and the Federation which triggered the Gnosis' arrival and caused Miltia to be swallowed in a space-time anomaly.

[6][7][8][9] The main characters are Shion Uzuki, a human scientist employed by Vector Industries, and her creation the prototype anti-Gnosis battle android KOS-MOS.

The attack begins mutating Cherenkov, tormenting him with visions of his past as a soldier who failed to adjust to civilian life and killed many people including his wife.

Alongside these events, the cyborg Ziggy is dispatched to rescue the Realian MOMO from U-TIC, as data stored inside her could open the way to the original planet Miltia, lost in a disaster for which her creator Joachim Mizrahi is blamed.

The group are forced to kill the transformed Cherenkov before escaping on the Elsa and being rescued by Jr.. During the subsequent battle, KOS-MOS activates previously-unseen weaponry and absorbs the attacking Gnosis.

Before fulfilling their mission, Nephilim tells them that KOS-MOS was designed to stop the energies of U-DO from entering their reality, an event which caused the original planet Miltia to vanish into a space-time void and could potentially destroy the universe.

Initially planned as a six-part series and despite there being concept work for a sequel, Xenogears was left as a standalone project while Square decided to focus on their established franchises such as Final Fantasy.

[15] Following his departure from Square due to disagreeing with their strategy, Takahashi searched for another company which could help him create the game he and others from the Xenogears project envisioned.

[18] Due to the amount of preparatory work and getting accustomed to the new hardware, actual development did not start until 2000, lasting approximately a year.

[21] The art director was Yasuyuki Honne, who had previously worked on both Xenogears and Chrono Cross, while character motion was handled by Norihiro Takami.

[25] To ensure development of the game remained focused, Takahashi consulted the entire staff on the script's direction before the main production began.

[18] Takahashi initially planned Xenosaga to span six games, with a narrative divided into three parts all featuring the dual figures of KOS-MOS and chaos.

[26] The game's subtitle is taken from the native title of The Will to Power, a collection of notes by German philosopher Friedrich Nietzsche.

The use of Nietzsche's works and concepts was a recurring element in the series; within the context of Episode I, the subtitle directly reflects the game's characters and the strength of their will.

[35] This version, with the English voice work and additional costumes and bonus features, was later released in Japan under the title Xenosaga Episode I Reloaded on November 20, 2003.

[43] Greg Kasavin of GameSpot enjoyed the narrative, but felt that the Biblical elements were only there for shock value rather than being meaningful additions.

[2] Jake Alley of RPGamer called the story "interesting",[5] while Eurogamer's Rob Fahey praised the complexity and depth of the narrative.

[55][56] Freaks was part of a movement with the Xenosaga series to turn it into a multimedia franchise, with the project growing substantially larger than previously planned.

[57] The sequel, Xenosaga Episode II, was developed by a new team with Takahashi overseeing the project so the series could be taken in a new direction by younger staff members within Monolith Soft.

The scenario, written by Norihiko Yonesaka based on the initial draft by Takahashi and Saga, ended up leaving out a lot of the originally planned content.

[63] Co-developed by Monolith Soft and Tom Create,[62][64] the scenario was supervised by Takahashi and included material which needed to be cut from the original releases of the first two Xenosaga games.