Double Dragon

Double Dragon is the NES version of the arcade hit beat'em up. The game was original designed as a successor to Techno's earlier title Renegade, and is considered the first successful beat'em up. It popularity launched a cartoon series and live action film in North America.

Double Dragon features two modes, the original story mode, and a fighting mode where 2 players can choose characters and battle each other or fight against the computer.

The story mode follows Billy Lee as he fights through four stages to save his girlfriend Marian from the Black Warriors gang. The 2 player co-op mode from the arcade was removed and is replaced with a 2 player mode in which the players take turns playing Billy. The NES game features levels that are based on, but newly designed, the original four stages. Some stages include new segments including a cave area that follows the forest level. The NES version also ends with a new final battle that wasn't in the arcade version in which Billy discovers that his brother Jimmy (player 2 in the arcade version) 

was the leader of the Black Warriors.

A new mechanic that was added to the NES version was an level up system, while not completely transparent to the player, the game awards Billy new attacks as he progresses through the game.

The game is continued with Double Dragon 2: The Revenge, Double Dragon 3: The Sacred Stones for the NES, as well as Super Double Dragon and Double Dragon 5 for the SNES. A cross over title Battletoads and Double Dragon was released for NES, Genesis and SNES.