Mega Man X6 (Rockman X6 in Japan) is the eighth game in the Mega Man X series, and is the first not produced by series creator Keiji Inafune. The PlayStation version was released in 2001 in Japan and the US within a European release the following year and in Singapore's AMK Hub in 2007. The game was released for the PC in 2003 as well, but only in Asia. The game was re-released on January 10, 2006 as part of the Mega Man X Collection for the GameCube and PlayStation 2. It is widely regarded as the most difficult game in the Mega Man X series, with some players who enjoyed the additional challenge while others deemed the game overly frustrating. Artwork was done by Haruki Suetsugu.
- Isoc - Gate's mysterious assistant, obsessed with finding Zero, even goes so far as to claim that he knows everything about him.
- High Max - A powerful Reploid created by Gate, supposedly built to investigate the Nightmare virus alongside his fellow investigators.
- Commander Yammark - Yammark was built as part of a project to help preserve nature. Unable to control his system, though, he accidentally burned down the forest he was meant to protect. He was never officially accused of the incident, but the Reploid Research team disposed of him by altering his flying system. He crashed and died. When he was revived by Gate, he felt he could trust no one and challenged X and Zero as a means to his own survival.
- Rainy Turtloid - Rainy Turtloid was created by Gate to investigate polluted areas. Due to his high protective ability, he could investigate areas not possible by any other Reploid. However, his defensive power frightened other Reploids, especially given that his creator was known to make Reploids that were unanalyzable and sometimes erratic. Requests to weaken him grew, but Gate opposed it. Rainy Turtloid was very loyal to Gate, trusting everything he said and did. Gate was to be punished for this, but Rainy Turtloid gave his life to save him. When Gate revived him, he once again layed down his life, this time for the Maverick Hunters, in order to defend his master.
- Shield Sheldon - Shield was a rookie bodyguard assigned to protect the famous Dr. Jim. Dr. Jim went Maverick and had to be destroyed, and Shield blamed himself for not protecting him from coming under the virus' influence. He was then labeled a Maverick by association. Unable to handle being labeled as such, he took his own life. He was then revived by Gate, swearing to protect him no matter what.
- Blizzard Wolfang - Wolfang was an investigator in the North Pole area, and his team was one day attacked by Mavericks. He managed to fend them off, but his team members were killed. The Reploid Research Team tricked Alia into killing Wolfang by throwing him into the sea. When he was revived by Gate, he insisted on using the second chance to complete his mission.
- Blaze Heatnix - Blaze was part of an investigation team and constructed specifically to handle hot areas. However, all those who fell behind in his party were murdered by him, and therefore he was disposed of by the Reploid Research Team. When Gate revived him, he occupied the Magma Area and was destroyed once again by X and Zero.
- Infinity Mijinion - Mijinion was a fiesty weapon tester. Though he always produced excellent results, he was brash in his decision making and didn't get along with his co-workers. The Reploid Research team destroyed him and made it look like an accident. When he was revived by Gate, he took hold of the Weapon Center and constructed a giant war machine known as Illumina. When X and Zero arrived, Illumina was active, but still in its testing phases. They destroyed the robot, and then met with Mijinion. He seemed arrogant at first, but later turned to rage when he realized that his creation had been destroyed. X and Zero disposed of him when he challenged them.
- Metal Shark Player - Metal Shark Player once worked for the recycling team and was eventually put in charge of the Recycle Lab. However, he was interested in DNA data and used it to revive felled Mavericks. Gate, also interested in this, encouraged him. However, DNA resurrection was strictly prohibited by law and he was dealt with swiftly. When Gate revived him, he took his place back in the Recycle Lab and continued to work on projects.
- Ground Scaravich - Scaravich was a treasure hunter bent on researching ancient data. Gate, interested in the data, took care of Scaravich in exchange for it. Gate then sent Scaravich to a forbidden area, where Alia promptly disposed of him as punishment. Gate didn't seem to care that he was disposed of, but revived him as part of his investigation team. When he was revived, he panicked upon seeing X and Zero, but then decided to challenge them for their DNA data.
The story begins three weeks after Mega Man X5, with Zero missing, presumed dead, and the Earth's surface rendered uninhabitable. Rumors are spreading through the Reploid World of a Maverick named the Zero Nightmare, a Reploid of pure evil that is spreading chaos throughout the world. X, curious about this Maverick, and angered by its use of his late friend’s name, seeks him out.
After destroying the Zero Nightmare, X learns that Zero is alive, just recovering from damage sustained in the last game. When Zero is recovered, he joins X and they seek out the researchers who built the Zero Nightmare.
X finds the lead researcher, Gate, in his lab. After X defeats Gate in battle, Gate reveals that he has rebuilt Sigma, the leader of the Mavericks. Sigma kills Gate, then challenges X to a duel. X is able to defeat the rebuilt Sigma.
- The game's short localization period (5 days between JP and US release dates) was due to an effort to rush the game out for the holiday season. This can be observed through the unaltered Maverick names, the retention of the Japanese opening and ending themes and voice acting (save the title and Maverick name calls), and a number of typos in the script, particularly found during the final battle ("THE BADDLE HAZ JUSD BEGUNN! DIE!! XXX! JUSDIE, X!!", "KID! I'LLSHOWYOUWHATATERRORISALLABOUT!! DIE! ZERO! JUSTDIE!! ZELLLLLLO!!")
- Infinity Mijinion's stage theme bears an uncanny resemblance to "The Final Countdown" by Swedish hard rock band Europe.
Director: Ohkoomi 16
Planner: Akiteru?, Toyozumi Sakai
Programmer: Masaharu Watanabe, Ryu Takada, Yoichi Isogawa, Humiaki Satou
Character Design: Kimio Yamazoe, Katsumi Toda, Tuyosi Fujisawa, Keisuke Ando, Akira Hirai, Masa, Yosinari Matuura
Background Designer: Ryutaro's Mama, Yoshitsugu Tanaka, Yanagimoto, Kenichi Miyahara, Satoshi Ueda, Daiki Ikeda, Yuji Yamamoto, Tomomi Fujiwara, Yosihisa Ueda, Syouji Hamada, Chiduru Hurukawa, Megumi Doi, Yasuaki Kisimoto, Chiduko Tamura, Yosika Seto
Original Design: Sensei, Komakisinsuke, Yama, Seito
Software Manual: M・ru
Sound: Tosio Kajino, Jyunko Hujitani, Akemi Kimura, Naoto Tanaka
Suleputer: Hidenori Shinohara, Mareo Yamada
Movie: Yoshimi Zaima, Yukiko Sasaki
GenAzea Staff: Erik Suzuki
Localization: Shizuku Abe, Kaori Funyakoshi
Voice: Syoutarou Morikubo, Ryoutarou Okiayu, Rumi Kasahara, Hirotaka Suzuoki, Wataru Takagi, Keiji Fujiwara, Takesi Aono, Mugihito, Norio Wakamoto, Hideo Isikawa, Sinichirou Miki, Yosinori Fujita
Tester: RōBAYAN '75, Kazuhisa Nisihara, Naoki Kamura, Atusi Nakagawa, Takashi Hashimoto
Public Relation: Yuko Nakamura
Special Thanks: Tomokazu Kadoue, Buppo, Sinichi Siohara, Jyunko Fujisaki, Syouhuu Oohasi, Koujirou Ogiwara, Jyunichirou Ogawa, Toshizi Hazumi, Mina Iwaki, Koichi Hase, Akiko Watanabe, and Capcom all staff
Producer: Tatuya Minami, Kouji Nakajima
Executive Producer: Yosiki Okamoto
Opening Theme - "Moon Light"; "The Answer"
- Syoutarou Morikubo
Ending Theme - "I.D.E.A. ~Boku wa Mainichi, Yume o Miru~"