Double Dragon II: The Revenge (ダブルドラゴンII ザ・リベンジ Daburu Doragon II: Za Ribenji?) is a side-scrolling beat 'em up produced by Technōs Japan originally released as a coin-operated arcade game in 1988. It is the first sequel to Double Dragon, released during the previous year. The sequel involves Billy and Jimmy Lee in a mission to avenge their girlfriend Marian after she is shot to death by the Black Warriors leader Willy, who is retaliating against the Lee brothers after his defeat at the end of the previous game. Double Dragon II was initially developed as an upgrade kit for the original Double Dragon, but evolved into a stand-alone game due to an increase in memory size, resulting in the developers reusing assets for both games.
Double Dragon III: The Sacred Stones, released in Japan as Double Dragon III: The Rosetta Stone (ダブルドラゴンⅢ ザ・ロゼッタストーン?), is a side-scrolling beat-'em-up produced for the Nintendo Entertainment System in 1991. It was the third Double Dragon game for the NES, developed by Technos Japan Corp. and published in North America and Europe by Acclaim Entertainment. Although loosely based on the similarly titled arcade game Double Dragon 3: The Rosetta Stone, it is not a port, but rather a parallel project that was developed at the same time.