Wario is, depending on who you ask, a thief, an adventurer, or a game developer. In truth, it's a little of all three. His first major crime, capturing Mario Castle in retaliation for Mario's childhood bullying, didn't go over so well, and ended with him booted out of Mario Land.

A number of unsuccessful revenge plots later, Wario decided he'd build his own castle- one better and more opulent than the Mario Castle the plumber left abandoned. One day, Wario learned that the Brown Sugar Pirates, led by the fearsome Captain Syrup, had stolen a massive golden statue of Princess Toadstool. With Mario already hunting for the statue, Wario saw an irresistible opportunity to show up his old rival: if he could find the statue before the plumber, then Princess Toadstool's ransom combined with the plunder of the Brown Sugar Pirates would give him enough money to buy a castle even bigger and better than Mario's. So Wario set out to reclaim the golden statue. After a long journey, culminating with a battle against the captain and her Genie, Wario escaped the collapsing pirate fortress with the pirate queen's loot. However, Wario's main objective, the golden statue of Princess Peach, was reclaimed by Mario (whom it was stolen from originally by Captain Syrup). Fortunately for Wario, the genie was so grateful for being freed from Syrup that he used his powers to make Wario his own castle! Of course, Captain Syrup would not take this sitting down, and captured Wario Castle with her pirate army! Flooding the castle and stealing the treasures, she ran off, leaving Wario to chase her around the world in pursuit of his ill-gotten gains. After fighting through a legion of bosses, he repaid Syrup by emptying out her treasure hoard, fueling the flames of their ongoing rivalry.

Wario's adventures continued, from the Music Box World to the five multidimensional corridors of the Ancient Pyramid. He started up WarioWare after discovering just how much money could be made from video games, and releases a new Mega Microgames now and again to experiment with evolving hardware. He invested his fortune in pharmacies, shipyards, and gold mines, and has seen a tremendous return. His most recent journey took him to the Shake Dimension, where he retrieved a bottomless coin sack... only to have it stolen by Captain Syrup. However, he managed to keep most of the OTHER treasures from the Shake Dimension, and his hoard is larger than ever. Of course, there's no such thing as enough treasure, and the multiverse provides an infinite amount of consequence-free plunder!