The original Mortal Kombat was the start of the new age of gaming.
The way it worked was Nintendo was trying to stay on Congress's good side by showing that it was not going to allow blood in its version of Mortal Kombat, but Nintendo's competitors were allowing the blood in their versions. So as it turned out that the competitors' versions ended up selling many more copies than Nintendo's so come time for Mortal Kombat II they were more than willing to put in the blood. Another part of what made Mortal Kombat unique was its "Fatality" specialty where one character would somehow graphically murder the other character in ways such as ripping his or her skeleton out his or her body in a graphic, bloody manner. From that point on many games would put on screen almost whatever they wanted if it looked cool. Some see this as the decline of video gaming, but I see it as a greater expansion of our tools with which to express ourselves in video games.
Playing this game is pretty simple: hit the other person, or thing in the case of Goro, until they are dead or unconscious. The music still scares me to this day. First that really haunting, aggressive music and then hearing the guy say "Fight!" The sound effects are not realistic, but then again they really do fit. The sound of a punch landing is very satisfying.
A truly revolutionary game, it changed the face of gaming altogether into something that our parents and legislation can truly complain about. Very nice.