I remember first encountering Double Dragon II in an arcade in Orlando when I was 8. Having been hooked on the original game the idea of a video game sequel to me (back then) was like a dream come true. To this day, I still kinda like DD2 despite it's many flaws, though I think nostalgia clouds the judgement of too many fans when it comes to rating the original games.
The game begins with Jimmy and Billy's shared girlfriend Marian being gunned down by Big Willy, leader of the Black Warrior gang, and so the "Revenge" of the title plays out. After all you went through to rescue her in the first game she's killed anyway. A bit of a bummer. But even at it's best, DD2 is just a copy of the original with some small changes made to the stages.
I stand by my previous reviews when I say that there has NEVER been a decent home console port of any of the games in this series, and DD2 on the Mega Drive (never released outside of Japan) is no exception. The game is very slow and sluggish, character sprites feel small, hit detection is very poor (always was), and it's not enjoyable at all as a brawler. They did manage to do a decent job of the music, however. So it's not a total bust. If you are a fan of the soundtrack to this sequel I recommend the the album, it's way better than the game it was composed for.
This series just did not age well and it was quickly overtaken by other brawlers such as Fatal Fury and Streets of Rage. Don't bother with this MD port, it's just not worth it.