Street Fighter 2010

Street Fighter 2010: The Final Fight, is a 1990 action platform game developed by Capcom for the Nintendo Entertainment System. The game is a futuristic themed action game where the player takes control of a cybernetically enhanced fighter who must fight against a breed of alien and mutant creatures in a series of boss battles. While not actually related to Capcom's Street Fighter series, the game is notable for its English localization, which changed the main character's identity and backstory from Kevin to Ken to imply that he is the same Ken from the original Street Fighter.

Story
Humankind sought a new land to claim. They began emigrating to other worlds. In this society made up of humans and aliens, atrocious crimes were committed. Thus began one of humanity’s darkest times...

The criminals were able to harness the incredible power of many cyborgs... but in 2010 AD, creatures called "parasites" with much more destructive power appeared. These parasites would merge with a body, causing it to grow a beetle-like shell of armor, and so bring forth considerably more power.

To confront this situation, the galaxy police sent the cyborg officer Kevin Striker. His orders are to destroy the parasites and gather their power, which would open a dimensional gate to the next area, though the gate would only remain open for 10 seconds, after which it'd close and Kevin would die. With this in mind, he sets out on his mission.

The U.S. manual states that the parasites (called in it a virus) was actually created by a society of scientists to make humans stronger and resistant to any climate, but it had gotten out of control. This fits with the Japanese version's introduction.

Localization Issues
Street Fighter 2010 was released in August 1990 in Japan and in the United States the following month, but due to changes between versions much confusion surrounds the game's transition from Japan to the U.S. It has been widely reported that Street Fighter 2010 was not a Street Fighter game upon its original release and that Capcom USA added the Street Fighter name when it came out in the U.S. to capitalize on the franchise's growing popularity. This account is not true: The game carried the same title in both countries for the most part. The sub title "The Final Fight", however, was added by Capcom USA.

To cash in on the Street Fighter name some more, Capcom USA went out of their way to change the story, and change Kevin's name to Ken. According to the US game's intro, Ken turned himself into a cyborg to make up for the gap between his time as "king of the street fighter circuit" to now (a gap of exactly 25 years given by the game, which would have meant Ken had won the first World Warrior tournament, when it was actually Ryu that had done so according to the later Street Fighter II storyline). The character's story was further altered to have him as the creator of the "cyboplasm" responsible for the mutants in the game, and a dead partner named Troy. The story from the U.S. version is shown below for comparison's sake:

"Ken had no interest in the Frontier, until his partner Troy was killed. Someone had broken into their lab, stolen their invention, and left Troy as a mere puddle of jelly on the floor. Even though it's been 25 years since Ken was king of the street fighting circuit, it's nothing a few good bionics can't fix.

Fortunately for him, the killer's path is very easy to trace. Every Frontier world the killer visited became quickly infested by the "cyboplasm" Ken and Troy had developed. In small doses, it gave people the strength they needed to remain alive, but an overdose and the cyboplasm would come alive, taking over the host's mind and body, turning them into mindless, violent mutants."

Although many games have been released that take place in the Street Fighter universe, no other game in the series references any element of Street Fighter 2010, leading to the possibility that the game has been retconned out of the official canon entirely. Furthering this problem, the rewrite by Capcom USA has resulted in a lot of confusion over the years, with many people believing that this was indeed Ken, and not realizing this is a separate character entirely, and a very separate game.