Earth

Earth (地球) is the main setting and backdrop for the Mega Man franchise. It is the third planet from the Sun and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets. It is sometimes referred to as the world or by its Latin name, Terra. Earth is home to millions of species, including humans. Both the mineral resources of the planet, as well as the products of the biosphere, contribute resources that are used to support a global human population. These inhabitants are grouped into about many independent sovereign states, which interact through diplomacy, travel, trade, and military action.

Original Mega Man universe
In the classic Mega Man series Earth has many similarities with the non-fictional Earth, but has much more advanced technology and, if Wily and Right's RockBoard: That's Paradise is taken as canon to any degree, different names for continents and/or nations. The whole planet and maps of it can be seen in many games, especially in the stage select screens from Mega Man 8 and Mega Man X5 to Mega Man X8.

Mega Man series
In the 21st century, with the advancement of science, humans were able to create industrial humanoid robots to help with different tasks, and they coexist peacefully. However, in the first Mega Man game, the scientist Dr. Albert Wily plans to take over the world, and the foremost authority on robotics, Dr. Thomas Light, modifies the helper robot Mega/Rock into the super robot Mega Man (Rockman) to stop Wily, starting a series of battles between the two scientists and their creations.

Not taking the defeat lightly, Dr. Wily created eight of his own humanoid robots in Mega Man 2. These eight were designed solely to fight and take down Mega Man. He sent them back to pick up where he left off in his previous attempt. Mega Man once again heads out to save the day.

After defeating Dr. Wily for the second time, the evil doctor vowed to mend his ways and make up for all his past mistakes by offering his assistance to Dr. Light once again. Together they built eight more robot masters and even began working on a giant peace-keeping robot called Gamma. Gamma was being constructed to keep the events of the past from ever happening again.

In order to construct Gamma, special crystals were needed. Dr. Light and Dr. Wily built special mining robots in Mega Man 3 to gather these crystal for them. During the mining process however some of the robots went berserk and drove out all of the humans. Mega Man was then sent to retrieve these special crystals for them, accompanied by his robotic dog Rush. It turns out that in the end Wily was behind the whole plan and was stealing the crystals for himself. As soon as he had stolen all of the crystals he activated Gamma and tried to use it to take over the world and defeat Mega Man. In the end Mega Man destroyed Gamma and had Wily in his grasp. The fighting had weakened the fortress they were in began to collapse and Mega Man was trapped under the rubble. Wily made his escape and the base still crumbled. Proto Man rushed in and saved his brother's life. However, Wily was believed to have died in the collapse of the base.

By Mega Man 4, Dr. Mikhael Cossack, a Russian Robotologist, was pressured by Dr. Wily into creating Robot Masters to attack the planet by holding his daughter, Kalinka, hostage. However, Wily was eventually found out by Mega Man, and Proto Man then retrieved Kalinka and returned her to Cossack, thus allowing him to not have to follow Wily's orders anymore, although Wily escaped after being defeated by Mega Man.

An entity resembling Proto Man was then sighted attacking various places on Earth, although it was later revealed to be Dark Man, a Robot created by Dr. Wily to frame Proto Man as revenge for the latter's betrayal of him. He eventually escaped again.

After going underground, Dr. Wily eventually assumed a change in identity as the millionaire Mr. X, as well as developing the X Foundation and hosting a tournament of Robot Masters. However, he then reveals his intentions of trying to conquer Earth. After briefly fighting against Mega Man and being beaten by him, X then unveils his true identity to Mega Man. After being defeated a second time, he attempts to escape, but is instead stopped by Mega Man, and this time placed in jail.

Unfortunately, Dr. Wily had anticipated the possibility of Mega Man also arresting him, and arranged for several robots to awaken and devastate the city he is being held at should he have failed to have escaped. He also had Bass, a robot he accidentially created alongside the energy source Bassium, fake allegiance to Dr. Light, and eventually also get himself wounded so he could steal a prototype Super Adapter. Wily narrowly managed to escape from Mega Man.

Mega Man X series
Dr. Thomas Light created a robot he named Mega Man X. X is the first of its kind to be able to think and make its own decisions. Fearing that this new robot could be dangerous, but lacking the time to find out for sure himself, Dr. Light sealed X in a capsule to be opened in the future when the robot’s loyalty could be determined, leaving a warning in the capsule in September 18, 20XX.

Time passed and technology advanced. In 21XX, a man by the name of Dr. Cain found X’s capsule and released the robot despite the warnings Dr. Light had posted on the capsule. This new scientist was immediately impressed by X’s advanced, human-like intelligence. Using X as a model, though there were things he had to change since he either didn’t understand how they worked or he wasn’t able to duplicate them, Cain created more robots similar to X which he hence called Reploids. Unfortunately for Dr. Cain, Dr. Light’s greatest fear came true. The new robots rebelled against humankind and became powerful enemies known as Mavericks.

Because of this, Dr. Cain is asked by the council to put a stop to this. He forms a special unit to stop these Mavericks known as the Maverick Hunters. However, the leader of the Hunters and Dr. Cain's creation, Sigma, goes Maverick himself, taking many of the Hunters with him. Thus, the "Maverick Wars" begins to take shape...

True and loyal, X took it upon himself to stop the Mavericks and Sigma. X wasn’t alone, however. He was almost immediately aided by the mysterious Zero. He also encountered capsules left by the late Dr. Light, which possessed holographic messages and useful power-up items from the scientist. Using these power-ups, X increased his meager abilities and brought himself back on par--and beyond--with his enemies.

During a climatic fight with the Maverick Reploid Vile, Zero destroyed himself to save X, allowing X to slay Vile. Alone now, X went on to defeat Sigma and bring the Maverick uprising to a halt.

Eventually more Reploids went Maverick, spawning a group of sane robots to form the Maverick Hunters. Led by X, they struggled to fight off the forces that were trying to eliminate all of mankind. During this, X discovered that Zero’s parts were in the hands of the X-Hunters: Agile, Violen, and Serges. X also discovered exactly into whose hands Zero was to be delivered - namely, Sigma.

Despite the odds, Zero was rebuilt, no worse for wear, and the Maverick Hunters put Sigma out of commission.

For a time.

This is where the tale of Mega Man X2 ends and the story of Mega Man X3 picks up. Dr. Doppler, a Reploid scientist, is possessed by a virus that is none other than Sigma himself, reduced to portable computer code. Sigma finds bounty in this form, however, since it allows him to inhabit whatever robot body he wants. He gets Doppler to construct for him a giant, invincible body, but almost before he can get inside it, X shows up at his front door to take him down.

Sigma’s third fall to a special anti-virus developed by Doppler is no more guaranteed to be his last than any of his others. In fact, he pops up perfectly healthy in Mega Man X4 to start a war between the Maverick Hunters and the Reploid military organization known as the Repliforce. He does it again in Mega Man X5 to cause a cataclysm related to the space colony Eurasia which crashes into the Earth. The Nightmare Phenomenon in Mega Man X6 which plagued Reploids and created some unusual circumstances, were the results of Reploid scientist Gate's experiments with a recovered sample of Zero's DNA from the Eurasia colony's crash site.

Sigma was also behind the attacks by a Reploid group called Red Alert in Mega Man X7, where Axl’s shape-changing abilities were the prize. In fact, Sigma even had his gloves in the events of Mega Man X8, although it isn't clear whether or not he is the one entirely to blame. It is yet to be seen what, if anything, will be required to finish Sigma off for good.

On the other hand, the Maverick Hunters, by now in full swing with X and Zero being the key players, are joined by Signas, Alia, and others helping behind the scenes, as well as the Reploid known as Axl who has become a full-fledged Hunter. Axl is a prototype to a new generation of Reploids which can copy the appearances and abilities of other Reploids. By the time of Mega Man X8, such Reploids are being mass-produced. This only resulted in chaos, and what humans remain are now attempting to flee to the Moon, abandoning the Earth to the mayhem that their Reploid creations caused.

Elf Wars and Mega Man Zero series
Shortly after the end of the long lasting Maverick Wars, the Elf Wars occur, a four year long conflict that ended with approximately 90% of all Reploids and 60% of all humans dying.

After the war, Maverick Hunters X and Zero have vanished from the view of the public and have become mere legends. Humans and Reploids find themselves at war as the humans have decided to stamp out all of the robots that caused the wars of the past.

Two factions emerge: some Reploids continue to serve the humans, even though the humans are in the process of systematically destroying most of the Reploids. The rest of the Reploids have fled, creating a Resistance force in an attempt to save themselves from annihilation.

Ciel, a human scientist, joins a group of these Reploids, who have constructed a Resistance Base as their place of operations. By studying Cyber-elves, Ciel hopes to develop a new source of energy that she intends to use to bring peace between the Reploids and the humans. Until then, they fight. Desperate to find a way to survive against the odds, Ciel revives the ancient warrior Zero, who had been locked away for an unknown span of time. Zero awakens with little to no memory of his past, but nevertheless finds himself facing the past when he battles Copy X, a duplicate of his historic partner, and leader of Neo Arcadia, the primary human government.

When the original X appears, it is in the form of a Cyber-elf. His body was sacrificed in an attempt to imprison the Dark Elf, the source of the Elf Wars that nearly devastated the world years ago. Now X serves primarily as a source of guidance, though he tends to give as little information as possible, revealing things incrementally.

Meanwhile, Dr. Weil, a scientist banished from Neo Arcadia for instigating the Elf Wars using a Reploid known as Omega, returns with a vengeance to attempt to accomplish his goals once and for all. He takes over Neo Arcadia and makes prisoners out of the humans as much as he wages war against the Reploids.

Mega Man ZX series
Legion created laws to give equality between humans and Reploids, and now both are treated equally as humans, living together in harmony.

One member of the Sage Trinity, Master Albert, created the Game of Destiny and made Mega Men fight against each other.

Mega Man Legends series
Several thousand years after the Mega Man ZX series, Earth (known as Terra outside Japan in this series) was covered by water, and humans now live on small landmasses. The original humans live on Elysium while bionic humans known as Carbons live on Terra. Before dying, The Master asked Mega Man Trigger to protect the Carbons and destroy the System, resulting in a series of battles that ended with Mega Man and Sera being sealed by Yuna for several years, and those events became legends. One day, the Digger Barrell Caskett found Mega Man Trigger sealed in a ruin and adopted him, naming him Mega Man Volnutt.

Mega Man Battle Network universe
Unlike the original series, the locations of the Earth from the Mega Man Battle Network and Mega Man Star Force series use fictional names, but still share many similarities to the real life Earth.

Mega Man Battle Network series
In 200X, most people have a PET (PErsonal Terminal) with a NetNavi. Humans use the humanoid NetNavis housed in their PETs for general use as Operators, although some work with their Navis in a sport called NetBattling, where an Operator uses Battle Chips to give their Navis special abilities to fight with, such as giving a sword or bomb. The series is centered around young Lan Hikari and his Navi, MegaMan.EXE, who both love to netbattle, and their adventures in the world, such as participating in a tournament (third and fourth games), or stopping a Net-criminal organizations like World Three, Gospel and Nebula.

Mega Man Star Force series
200 years later, the Internet-based technology was replaced to an EM Wave-based technology, EM Beings replace NetNavis (although some Navis can still be found, according to the first game of the series), and no one uses a PET anymore (in the series, there is a reference to the PETs - in the first game within the junk yard, there are a bunch of discarded devices, and when looked it will say a popular device that was used by almost everyone, although now useless).

The Net is replaced by the EM technology, which created the Wave Road, which exists in the real world, but impossible for humans to see (unless using a Visualizer). Among the Wave Road, there are EM Viruses that are deleted by the Satella Police using Battle Cards (in which a later game can be deleted by anyone using the Star Carrier or Hunter-VG), or other EM beings, usually Mega Man. With the use of three satellites, controlled by the Satellite Admins, the whole Earth is connected using the Sky Wave (and later the Astro Wave), which transcend to space (Outer Astro Wave) and other planets, such as Planet FM and Planet AM.

The series centers around Geo Stelar, a 12 year old boy who lost his dad Kelvin Stelar in a space accident, and the fugitive AM-ian, Omega-Xis, who can change Geo's frequency in a way called EM Wave Change, fighting villains such as other FM-ians and other antagonists, such as Le Mu and Dealers.