The plot begins when narcotics agents Paul and Bobby are committed to putting an end to the drug syndicate known as "MID".

When Paul heard the voice of his girlfriend Catherine crying for help on the phone while being hung up without explaining, he assumed she's been abducted, making him and Bobby head toward Riot Island and save her.

Riot City resembles Capcom's 1989 arcade hit, Final Fight, which is an archetypal side scrolling beat-em-up game.

[1] Player one controls Paul the blond-haired with balanced fighting skills, and Bobby the tough, but slow break-dancer from left to right through each level (most of which are split into three or more scenes), fighting with the enemy characters who appear, until they reach a confrontation with a stronger boss character at the end of the level.

While Westone decided to create a modified version of Sega's Wonder Boy for Hudson Soft as Adventure Island for the NES, they also took Riot City, remade and ported it to the TurboGrafx-CD as Riot Zone (known in Japan as Crest of Wolf (クレスト オブ ウルフ or 狼的紋章)).