Zero Space

Rei Space (零空間) is the final stage from Mega Man X5, a Cyberspace area that materialized in the real world in point 11F5646 because of the Zero Virus. The Rei Space consists of four stages, each which X and Zero must go through to investigate.

Characteristics
Zero Space is a spatial anomaly created after the space colony Eurasia either crashes or is destroyed. The affected area turns into a facsimile of Cyber Space, resulting in a digitized atmosphere. The structures in Zero Space are composed of flat surfaces with transparent foundations patterned after circuitry. Massive amounts of data flow continuously in the background, which changes color between the first three stages (from blue to purple, then red). The background reverts to blue in the final stage, but the pattern changes into a series of complex circles which rotate endlessly.

The Zero Virus thrives in this environment, and its power allows even programs to escape Cyber Space and make their presence here.

Canon
Although the Earth is saved, Zero is still bothered by his unusual reactions to the Sigma Virus and upon learning about the creation of the Zero Virus, he decides to investigate Zero Space for clues. Concerned about Zero's viral readings, X decides to stop him, but Zero refuses to return and a fight ensues. The two Hunters reach a stalemate, knocking each other out. Sigma attempts to use the opportunity to destroy the unconscious X, but Zero recovers in time to repel Sigma, who decides to retreat. Sigma is soon defeated, but his explosion leaves Zero severely damaged. When X arrives to help him, Sigma's head fires a laser through X's back, just before Zero lands a final shot with the Z-Buster. Zero dies soon afterwards, but X's body is found and restored by an unidentified entity as Zero Space vanishes.

Non-canon (Eurasia crashes)
Following the fall of Eurasia, Zero is infected with such quantities of the virus that his true self begins to shine through, turning Zero into an evil robot bent on destroying X. Feeling the evil in Zero, X accepts the challenge and rushes to confront him deep in Zero Space. The two Hunters are knocked out and Sigma tries to use the opportunity to destroy X, but Zero shields him with his body, dying with the attack. Sigma retreats, but he is followed by an outraged X, who defeats him after a hard battle. Sigma's explosion leaves X critically injured, but he is restored by an unknown entity who also decides to erase "all the painful memories". X returns to the Hunters afterwards with no memory of Zero.

Rei Space Stage 1: Origin
The first Rei Space stage, Origin (起源), is the entrance to the Rei Space. The area protected by lethal lasers. X/Zero need to dodge the lasers or use Dark Hold to pass the area safely.

This stage bears a striking resemblance to Quick Man's stage from Mega Man II, if not being a complete copy of that area.

Enemies:
 * Eagle G
 * Spike Marl
 * Zero Virus

Boss:
 * Shadow Devil



Rei Space Stage 2: Grief
The second Rei Space stage, Grief (哀愁), begins with a vertical area with spikes and enemies and ends in a horizontal area that needs to be climbed by using ropes and Wall Kicks while avoiding the enemies and spikes.

This stage bears a striking resemblance to Sigma's Fortress 1 from the original Mega Man X, if not being a complete copy of that area.

Enemies:
 * Crusher NEO
 * Eagle G
 * Hover Gunner
 * Sniper
 * Walk Shooter
 * Zero Virus

Boss:
 * Rangda Bangda

Rei Space Stage 3: Awakening
The third Rei Space stage, Awakening (覚醒), has several spikes and pifalls across the path. In one small pit, there is a hidden capsule. As X (without armor), Dr. Light gives the Ultimate Armor. As Zero, Dr. Light improves his abilities, changing his color to Black Zero. It is possible to obtain both by dying in the stage and return with the other character.

Enemies:
 * Metall T
 * Hover Gunner
 * Seil Gabyoall

Boss:
 * Zero / Awakened Zero (as X)
 * X (as Zero)

Rei Space Stage 4: Birth
The fourth and last Rei Space stage, Birth (誕生). The stage has spikes in the beginning, a rematch against the eight stages bosses, and a large pit with Appearing Blocks.

Enemies:
 * DejiraShot13.gif
 * Eagle G
 * Hotarion
 * Killer Sphere
 * Spark Gunner
 * Spike Marl
 * TriScan Gold

Boss:
 * Rematches: Mattrex, Dark Dizzy, Izzy Glow, Squid Adler, Duff McWhalen, Grizzly Slash, Axle the Red, The Skiver
 * Sigma

Trivia

 * Another possible translation for "零空間" is "null space", which may be a direct reference to the concept of null space of linear algebra.
 * In the collected soundtrack, the two themes for Zero Space are labeled "ZERO STAGE 1" (used in the first three stages) and "ZERO STAGE 2" (used in the final stage).
 * Zero Space is located in point 11F5646.
 * The stages of Zero Space make several throwbacks to past games of the classic series and the X series.
 * The lasers of Zero Space 1, as well as most of the layout are based off Quick Man's stage. The lasers can be stopped with the Dark Hold, similar to how the originals could be halted with the Time Stopper.
 * Zero Space 2 has a strikingly resemblance to the first stage of Sigma Palace in Mega Man X. The boss, Rangda Bangda W, is a new version of Rangda Bangda, complete with a remix of the original fortress boss theme from Mega Man X.
 * The music in the final stage is a remix of Quickman's theme from Mega Man 2
 * The vanishing blocks in Zero Space 4 are very similar to the ones that appear in many games of the classic series.
 * In Mega Man Zero 3, new rifts to Cyberspace are created by the resonance between Omega and the Dark Elf; however, the Cyberspace featured in this game does not have the digitized aspect of Zero Space.