"Maybe the most underrated game ever..."
Overshadowed by Double Dragon, River City Ransom is a largely unknown game that far exceeds its beat-em'up trappings. Following the traditional "Girl gets kidnapped by gang members, Heroes fight gang members, Heroes win girl back" storyline, it won't win any fans for originality in story, but this game was a microrevolution in an eight bit cartridge.
Two players could team up, or you could single handedly march through the streets of River City, beating up every gang member who got in your way. Unlike Double Dragon, however, the game was not linear. You could wander the streets, defeating different gangs, purchasing food, talking to people, purchasing books to learn new techniques, etc. This was debatably the first real martial arts action RPG.
With two players, team combo moves could be learned. This game was fascinating, because you had character progression in a beat-em'up game, which was unheard of. In fact, it was so unexpected that it may have missed its original market. This is one that anybody who reminisces about the eight bit glory days should give a shot. It's truly a classic. The team who developed this game also made the classic Super Dodgeball.