Fist Puncher is a side-scrolling brawler with 8-bit-style pixel graphics. The plot is to rescue beauty queens who were kidnapped by the evil Milkman. The basics of the game are simple: the player character moves from left to right and beats up all opponents. Some of the 50 levels - which are accessed from a city map with branching paths and can be replayed at will - also have gimmicks like a time limit or a motorcycle ride. The locations are varied in topic - e.g. a slaughterhouse, a Nazi-KKK hideout or a strip club - and are played for laughs.
The focus lies on melee combat, although sometimes items can be thrown at enemies. Each of the player characters has a set of standard moves (jumping, kicking, punching, grabbing and a evading roll) and individual special attacks which drain a automatically recharging power bar. Each fight rewards experience points; after level-ups the player can improve the main stats like strength or speed and buy new special moves like healing. Collecting power-ups, mostly dropped by dead enemies, brings advantages like filled-up health; the most important are the letters R, A, G and E which cause the characters to temporarily leash out a lot of damage when the set is completed.
Otherwise the game also features unlockable characters (overall 17 including the starting characters), easter eggs, in-game collectible cards (rewarded for achievements), and a local co-op mode.