The special parts can help X & Zero in certain ways. The game has over a hundreds missing reploids in the game's levels - some of the Reploids offer specials parts that X or Zero can use. Once the player collects enough, the character's ranking will go up, which allows the characters to have access others special parts that are obtained from missing Reploids, found in various locations throughout the game's eight Maverick stages. Mega Man X6 offers a leveling system, and the way a character can level up is by obtaining souls from certain Mavericks. This is important because this game has many more hidden secrets to find than the other games in the X series. The game features a "Nightmare" system, which makes it so that when X or Zero defeats a Maverick, their icon on the level select screen will become red, which means that certain environmental hazards will be added to the level to increase difficulty. The game starts off with X, but Zero can be unlocked later.
The game was later released for the PC in different parts of Asia sometime in 2002-2003 and is included in the Mega Man X Collection compilation for the PlayStation 2 and GameCube (released on January 10, 2006).
When Reploid scientist Isoc (along with his subordinate, High Max) identify the cause as the "ghost" of Zero, X (now brandishing Zero's Z-Saber) must investigate the Nightmare phenomenon (while encountering infected researchers of the virus, who were created by lead researcher Gate) and stop Zero's Nightmare doppelganger. A new and mysterious virus, known as "Nightmare", is turning Reploids into crazed Mavericks.
Set in 21XX, the game takes place three months after the events of Mega Man X5 (where Maverick Hunters Mega Man X and Zero prevented a massive space colony from fully destroying Earth and eliminated Maverick Sigma yet again, with Zero sacrificing himself to save X).
The sixth main installment of the Mega Man X series (and the sequel to Mega Man X5), Mega Man X6 is the last game in the franchise to feature a 32-bit style (in both graphics and gameplay). Mega Man X6 (known in Japan as Rockman X6) is a side-scrolling action platformer developed and published by Capcom for the PlayStation on December 4, 2001.