Earthworm Jim

The game plays as a 2D sidescrolling platformer with elements of a run and gun game as well. The player controls Jim and must maneuver him through the level while avoiding obstacles and enemies. The player can use Jim's gun as a method of shooting enemies, or his head as a whip for whipping enemies. The whip move also allows the player to grab hold of, and swing from, certain hooks in the game. Some levels have additional requirements beyond merely getting to the end of the level. For example, the level "For Pete's Sake", involves making sure the computer-controlled Peter Puppy character gets through the level unharmed, which is accomplished by whipping him to make him jump over pits, and defeating enemies before they can damage him. Failure to do so results in Peter lashing out at Jim, taking away from his health.

Levels commonly culminate with a boss battle. The game incorporates a large variety of villains in the boss battles, including Psy-Crow, Queen Slug-for-a-Butt, Evil the Cat, Bob the Killer Goldfish, Major Mucus, and Professor Monkey-For-A-Head. Two villains made their only appearance in this game, Chuck, a junkyard man with a stomach bug, and Doc Duodenum, a crazed organ.

In-between most levels, a racing level called "Andy Asteroids" is played. Unlike the rest of the game, it places the viewpoint behind Jim. The player must direct Jim on his rocket, in a race against Psycrow, through a tube-like structure while collecting items and boosts and avoiding asteroids. If the player wins, the next level is started instantly. If the player loses, a special boss fight against Psycrow must be won in order to progress to the next level.

Other variations in gameplay occur over the course of the game as well, such as a competitive bungie-jumping and fighting level, and an underwater maze that must be traversed both within a timelimit and without crashing too many times.