Doctor Brown, a scientist, perfected a time travel machine, and organized the "World Heroes" tournament for various fighters throughout all of history to combat each other. True to this plot, many of the fighters are based on actual historical figures.
According to ADK World, other famous people considered for the cast were Al Capone, Billy the Kid, Musashi Miyamoto, Napoleon, and Jack the Ripper. An Egyptian and a Korean warrior (the game's intended sub-boss) were also in the works. Out of the entire prototype lineup, Hanzo was the only one kept for the final product. Jack was redesigned and later added to the cast in World Heroes 2 Jet.
World Heroes is a 2D fighter by ADK made during the fighting game craze and follows the same format as many of the other fighting games. Instead of a 6-button layout, World Heroes uses only 3 of the standard 4 Neo Geo buttons: one for punching, another for kicking, and the last for throwing. The former two buttons can be held pressed longer in order to deliver stronger attacks. The game has two game modes: the Normal Mode, with own stages and the Death Match Mode, with personalized battle stages.
When fighting in Death Match arenas, there are obstacles which can control the tide of the battle. Ground obstacles can cause fighters to slide forward or backward to their (dis)advantage, or lose a limb by stepping on landmines. Wall obstacles can electrocute, burn or impale fighters thrown upon them, knocking them down for extra damage. Fights will never be the same for arenas with both ground and wall obstacles at the same time for extra humiliating defeats. Be careful of a match where your hair is at stake!
- Hanzo, the protagonist of the game, is the head of the Iga ninja clan, during the Ashikaga Shogunate. He is sent to a world unknown to him. He also continues to train and obtain enlightenment as a warrior, and considers himself naive, though he has hopes to one day be the greatest. His rival is Fuuma Kotaro, head of a rival clan.
- Fuuma Kotaro, the fifth leader of the Fuuma ninja clan and Hanzo's rival. Unlike his enemy, he's an easy going womanizer who doesn't like to work any harder than he has to. He also adopts to the new culture that he's in and is excited by change.
- Kim Dragon, a famous martial arts movie star in the 20th century. His career is compared to that of singers, but he wants to be a great fighter as well. He enters the WH tournament to prove his point.
- Jeanne D'Arc, a French swordswoman from the 15th century. A bearer of a tremendous beauty, she roamed her land in search of a strong fighter to become her husband. However, she continues her search in a different time now.
- J. Carn, a Mongolian warrior, he is the strongest fighter of his people. He led the powerful army into many victories and conquests.
- Muscle Power, an American star pro wrestler, who strongly believes that his own power of his muscles is #1. He fights in the World Heroes tournament to prove it. He dreams of making a name for himself in the pro wrestling world.
- Brocken, is a robot developed by Dr. Brown initially for the Nazi army. After their final defeat in World War II, he travels the world to prove that the power of science is the greatest of them all.
- Rasputin, the leader of a love cult based on Russia. He is also a sorcerer with great knowledge in magic, and fights the other World Heroes, preaching about the love all mankind should have.
- Geegus, an artificial polymorphic being from the future, created by a mad scientist named Damned. It is sent to the past multiple times to kill anyone that crosses its way, intending to take over the Earth.
- Note: Throughout the game, there will be a bonus stage (Kim Dragon's stage) given for every 3 completed matches (After Battles 3 and 6). The player is given a task to "destroy everything" within 30 seconds. Failure to do so still earns points, but if successful the player earns a huge point bonus! If a challenger comes into play, the bonus stage resets for a fresh start. The player who performs better gains the upper hand bonus. The players both have infinite life in these stages. The bonus stages are as follows:
- BONUS GAME 1: SMASH THE STONE: After Stage 3 is the first bonus game: strike the huge slab of stone until you carve out a statue. You are given 30 seconds to strike the slab with ALL your character's moves. Use your punches, kicks and special attacks.
- BONUS GAME 2: DESTROY THE POTS: After Stage 6 is the second bonus game: crush all 15 pots. These pots drop from the ceiling and roll on the floor once they touch the ground. Ten pots fall within the 30 second limit, so destroy them all before they topple you.
Marketplace — Hanzo: The Kaminarimon, the larger gate of the Sensō-ji temple, in the district of Asakusa, Tokyo (Edo in this time). Features some people, red and green structures, Kanji signs and the statues of Fūjin and Raijin, Buddhist gods.
Monkey Park — Fuuma: The Lake Kawaguchi, next to the Mount Fuji, in the cities of Fujikawaguchiko and Minobu. The fight takes in the Panoramic Ropeway. Features grass floor, a ladder, a sidewalk and dressed monkeys.
- Note: the vases can be broken by the players.
Circus Camp — Jeanne: The main entrance of a circus in Paris, at night. Features people, a clown, a circus ball, carts, a red carpet and a tamer driving a car with a lion in a cage.
Cage Match — Muscle: A meshed platform above the city of New York, at night. Features spotlights, insulation strands in red, yellow and blue and a grey zepellin with the neon sign FIGHT, besides the Empire State Building, the Statue of Liberty and the Brooklyn Bridge, in the background. A similar version of the stage can be seen in The King of Fighters XIII.
Military Base — Brocken: The fight takes next to a platform passing on the Ramstein Air Base. Features protected pipes, war tanks, aerial bombs, lamps, airplanes, green metal barrels and a metal door with the sign Abw Abt.
- Note: the metal barrels can be tipped by the players.
- Note: The wooden barrels can be broken by the players.
Space Station Base: The main salon of a spacecraft orbiting the Earth. Features blue crystals, a red structure, a throne and blue crystals. Associated with Geegus.
- Note: the crystals can be broken by the players.
Death Match Battle Stages
This stages are only available in the Death Match Mode.
- Note: All the stages featured the same audience cheering next to the arena, with variations of athomsphere and present things .
High Energy — Hanzo: The stage is a ring with a blue floor and electric insulation cordons that, when the player touches him, is automatically electrocuted.
Needle Oil — Fuuma: The stage features a red structure, two oil puddles and thorn walls, in the both sides.
Oil — Dragon: The stage is a ring with blue insulation cordons, a grey floor, two oil puddles and photographers.
Hair Splitting — Jeanne: The stage is a ring with green insulation cordons, a yellow floor and photographers.
Fire — J. Carn: The stage is a ring with a red floor and burning insulation cordons.
Landmine — Muscle: The stage is a ring with red insulation cordons, a red floor, photographers and landmines that, when activated, burst and cover the player with fire.
Needle — Brocken: The same stage as Fuuma, but without the oil puddles.
High Energy Oil — Rasputin: The same stage as Hanzo, but with the oil puddles.
High Energy Landmine: The same stage as Hanzo and Rasputin, but with the landmines. Associated with Geegus.