Description taken from Arcade version of this game

Mortal Kombat is a 2D fighting game with digitized actors for characters and a five-button control system. There are two sets of punch and kick buttons for high and low strikes. The fifth button is designated as the block button. After winning his or her second round against an opponent, the victor has the option of performing a fatality. The defeated opponent will stand dazed for a few seconds, during which you can perform a specific button and joystick sequence to kill the opponent in a particularly gory way. Fatalities have no actual effect on gameplay, but because of their bloody nature Mortal Kombat is meant for mature audiences only.

Every great fighter aspires to participate the Mortal Kombat tournament. Being invited is a great honor, as it means that you're considered one of the best fighters in the world. The tournament is held once each generation, and the winner is recognized as the greatest fighter of his or her generation.

The latest tournament is being hosted by Shang Tsung, a powerful and evil wizard. Seven fighters will be participating, each with his or her own reasons for competing. The victor will have to fight against Shang Tsung's inhuman champion Goro, and then against the wizard himself. ~ Kyle Knight, All Game Guide