Development began in 2000 under the codename "Project X" following the founding of Monolith Soft. Intended as a spiritual successor to the 1998 video game "Xenogears", multiple staff were carried over including director and co-writer Tetsuya Takahashi, co-writer Soraya Saga, character designer Kunihiko Tanaka, and composer Yasunori Mitsuda. The game received generally positive reviews from critics and sold over one million copies worldwide. Its direct sequel, "Xenosaga Episode II", was released in 2004 in Japan and 2005 overseas. The final "Xenosaga" game, "Xenosaga Episode III", was released in 2006. The game received an which aired in 2005, and was re-imagined along with "Episode II" as part of "Xenosaga I & II" for the Nintendo DS.