The World Warrior

Street Fighter II was a 2d competitive fighting game released in arcades in 1991. The original version’s full title was Street Fighter II: The World Warrior. It was later released for various consoles, and then updated with new versions such as Street Fighter II: Hyper Fighting and Super Street Fighter II Turbo. Street Fighter II was critically acclaimed and established competitive fighting games as mainstream. Some gamers and magazines at the time were even describing it as the greatest game ever made. It completely overshadowed its predecessor, the original Street Fighter. Street Fighter II Turbo, or Super Turbo as it's called, is still played by competitive gamers in tournaments to this day.
Street Fighter II had one really big innovation that set it apart from games of the same genre that came before it. Players got to choose from one of 8 characters, and each character played differently (except Ryu and Ken who were palatte swaps) by having different move lists. This created a lot of depth and replayability, especially for an arcade game.
Another quality that helped the popularity of Street Fighter II was its presentation. Street Fighter II had heavily detailed characters and backgrounds. The backgrounds are full of crowds of cheering people and other animated things such as animals. It also had a different location based background for each of the characters.
The last the thing that really made Street Fighter II stand out was the controls. Previous fighting games had relied on two button control schemes. Street Fighter II had six buttons, each of which correlated to different attacks. The joystick used was also more responsive than the ones used in previous games. As a result, the control scheme was much tighter and more fluid control scheme than previous games.
When Street Fighter II came out, arcades were on the decline, especially in the United States. Console games were on the rise and becoming more popular, and as a result, less people were venturing out of their homes to the arcades to play games. Street Fighter II managed to postpone this decline for several years. People would train at becoming good at the game, and then they would gather at arcades to play against each other and show off their skills. Crowds would then form to watch as the local experts would duke it out in front of everyone. The winner would stay on the machine to take on more competitors, while the loser would be forced to go to the back of the line. It became quite a social experience for everyone involved, almost like a sporting event. Street Fighter II developed its own community.
This inevitably led to tournaments being held for the game where the top players from all over would meet and play against each other. Capcom recognized how popular Street Fighter II was as a serious competitive game, and as a result, they released several updates to the game throughout the years that addressed several balancing issues in the game. Super Turbo is considered one of the most balanced fighting games and is still played competitively at fighting game tournaments.
Another interesting phenomenon that arose from the Street Fighter II community was the rumors that people created related to the game. The four bosses in the game (Balrog, Saga, Vega, and Bison) were not selectable in the original version of the game. Many people speculated on various ways to unlock them for use, even though no actual way existed. Other rumors existed around possible secrete characters (such as Sheng Long) and secret special moves.
The game was played so much that people also found various glitches in the game, so of which were later recognized as features and intentionally incorporated into future games. For instance, it was discovered that certain moves could strung together so that they could not be blocked if the first hit connected. These later became known as combos, and they are now a staple of the fighting game genre even though they were originally just a programming oversight.
With the advent of the internet, the Street Fighter community also went digital. There are many communities and informational resources for Street Fighter online. Early on, people discussed tactics and tricks on Usenet and IRC. Even now there is Shoryuken which is a large community that is devoted to competitive games. Shoryuken draws its name directly from one of the signature attacks of Ryu and Ken from Street Fighter.
Street Fighter II spawned many competitors in the years after its arrival. Games such as Mortal Kombat, Killing Instincts, and Virtua Fighter were all inspired the mechanics and success of the Street Fighter series. Pretty much the entire versus fighting game genre has Street Fighter to thank for establishing the genre as mainstream.
The Street Fighter series is still being added to, with a large following of people deeply interested in the next game the series has to offer. Street Fighter IV was recently released in arcades (with people anticipating a console release in 2009), and people are already scrambling to find the best characters and strategies in the game. Also, Super Street Fighter II Turbo HD Remix, which is a further rebalance of the original Street Fighter II, is being released on the Playstation Store and Xbox Live Arcade later this year. It seems like this series has such a large following that it will never die.
Street Fighter II has left quite a legacy. Very few games have developed as large and devoted community as this game. It was one of the earliest games to develop a competitive tournament community focused around it. Overall, Street Fighter is one of the defining games of the early 90’s, and will be remembered for its enormous impact on future games and the development of game related communities.

Sources
http://www.sega-16.com/feature_page.php?id=141&title=History%20of:%20The%20Street%20Fighter%20Series
http://www.gamespot.com/features/vgs/universal/sfhistory/index.html
http://users.tkk.fi/~eye/videogames/arcade.html
http://www.shoryuken.com/wiki/index.php/History#Beginnings