To learn about and understand the hellish place called Murderworld, one first must learn about its psychotic creator, funder, and user: the madman known as Arcade.
Murderworld is constantly changing to fit the unlucky person stuck in it. There are many Murderworld facilities, designed for a different hero. For instance, when Thing was trapped in a Murderworld, Arcade designed robot versions of the past versions of the Hulk, such as Maestro and Joe Fixit. Poor Thing had to fight each one, right in a row. He barely made it out alive. There are a few small idiosyncrasies of Murderworld. Murderworld is designed like an amusement park or a carnival. Clown-robots, huge flowers that squirt acid, bumper cars with spikes that go towards someone at 100 mph, all the traps are somehow carnival related. It costs 1,000,000 dollars to send someone to Murderworld, although Arcade doesn't need it. Only two people work with Arcade on Murderworld, the mysterious Miss Locke and Mr. Chambers. They clean out Murderworld, fix traps, feed Arcade, create new traps, organize files, whatever is needed to keep the carnival going. Almost nothing is known about them. Arcade has one similarity to Joker, too-unlike your typical mastermind who believes his trap is unbeatable, Arcade leaves a tiny, miniscule chance for his victim to escape. This is often his downfall, but Arcade has a simple reason. "If you're going to kill them, at least have the decency to do it quickly, painlessly!" said someone who learned about Murderworld. Arcade laughed and replied, "Decency's dull... besides, miss, your way, they're dead and that's that. My way, they've got a chance. Not much of one, but a chance."
The first people ever caught in Murderworld were a duo. In Marvel Team-Up #65, Spider-Man and Captain Britain were trapped in Murderworld. They made it out, but were shaken by the experience. It was the world's first taste of Murderworld. Over the years, many victims were trapped in Murderworld, including Longshot, Phil Urich(also known as Green Goblin), Ghost Rider, and Doctor Doom. He also fights teams like X-Men, X-Factor, Alpha Flight, Excalibur, and the Micronauts. And occasionally, two people get trapped in Murderworld and have to fight out together. Examples are Wolverine and Gambit, Archangel and Iceman, and Colossus and Kitty Pryde. Murderworld hasn't killed any major heroes yet. Recently, Arcade sold one of his Murderworlds to Viper, who tried to kill a powerless Storm and the Queen of England. However, they escaped.
Murderworld has also been reduced to a traveling show, bringing the entertainment in a more versatile manner. One stop was in Phoenix, Arizona, where Arcade kidnapped Shatterstar and Adam X and pitted them against each other, controlling the action with mind games. Neither man died, however, and Arcade escaped due to the fact that an android acted as proxy.
In the Ultimate universe, Arcade is an assassin but does not use Murderworld. It is only mentioned as the name of a video game he designed which got him his fortune.