"River City Ransom: Underground" is a beat'em up game where players help a new group of fighters defeat hordes of enemies in a sprawling city. The game features over 500 moves, various weapons, and secrets to discover, with the ability to play online co-op with up to 4 players. The story campaign includes 10 playable heroes, 140 levels, and 22 shops to upgrade characters, while the arena multiplayer mode allows for customizable battles with 44 unlockable fighters.