Double Dragon

Double Dragon is a beat 'em up video game series initially developed by Technōs Japan. Due to the popularity of the game series, an animated series and live-action film adaptation have also been produced.
The original Double Dragon by Technōs was first released as a coin-operated arcade game in 1987. A NES version also produced by Technōs was released in 1988.

Original description:

Double Dragon is the story of Billy and Jimmy Lee, twin brothers who learned to fight on the cold, tough streets of the city. Their expert knowledge of the martial arts combined with their street smarts, has made them both formidable fighting machines.
But now Billy is faced with his greatest challenge. Marian has been kidnapped by the Black Warriors, the savage street gang of the mysterious Shadow Boss! Using whatever weapons come to hand - knives, whips, bats, rocks, oil drums, even dynamite - Billy must pursue the gang through the slums, factories, and wooded outskirts of the city to reach the hideout for his final confrontation with the Shadow Boss... his brother Jimmy!

Instructions

Enter - start (pause);    Space - start, select mode;    Arrows - move;    Z - kick;
X - punch;    Z + X = jump kicks;
2x RIGHT or LEFT - headbutt in Mode A, run in Mode B;    Esc = exit fullscreen;

You can change keyboard settings, save (F5) and load (F8) the game.
Put your mouse over the game and choose your settings, you can also play the game in fullscreen.