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Star Chips were star-shaped, golden-colored trinkets used in the Duelist Kingdom tournament. At the beginning of the tournament, each invited Duelist received 2 Star Chips and a Dueling Gauntlet with 10 slots to hold them. Duelists waged their Star Chips in Duels against each other, with the loser handing over the wagered Star Chips. If a Duelist ran out of Star Chips, they were disqualified; exchanging Star Chips outside of a Duel was a violation of the rules, and being caught would also result in disqualification. If a Duelist won 10 Star Chips, they could use them as a "key" for the front gate of Pegasus Castle, where the finals were held.
Originally, Katsuya Jonouchi and Keith Howard did not have any Star Chips nor Dueling Gauntlet, as they were stowaway participants, but got their hands on both requirements in their own ways to enter the castle.
Seto Kaiba, being a "special guest", was given the five Star Chips his brother Mokuba Kaiba stole and confiscated by Saruwatari. (In the anime, Pegasus gave Seto five extra Star Chips out of his own supply, as the ones Mokuba stole were thrown into the ocean.)
Eliminators, like PaniK, were able to hold far more than the standard 10 Star Chips, as they possessed a much larger Dueling Gauntlet on each arm. There were 80 Star Chips issued to players in total, and the Eliminators were assigned to retrieve 40 of them to ensure that it would be impossible for more than four finalists to enter the castle.
Star Chips are used in Yu-Gi-Oh! Forbidden Memories as rewards for how well the player does in a Duel. The Chips are also used for Password Cards, where the player can input the Passcode for a card, and the the player must then pay up the amount of chips needed to "buy" the card. Some monsters require little, such as "Dancing Elf", which requires 10 Star Chips, while others, such as "Blue-Eyes White Dragon" require 999,999 Star Chips. Cards can only be purchased at the Passcode screen and not in the card shop.
In Yu-Gi-Oh! Monster Capsule GB Star Chips are used as currency and anted on duels, with a certain number required to progress on each floor of the tower. They can he spent to buy new Capsule Monsters, and in the postgame spending 98 of them in the basement's machine after rescuing all of Yugi's friends will get you a Yugi figurine.
Star Chips are bonus items in Yu-Gi-Oh! 5D's World Championship 2010: Reverse of Arcadia and Yu-Gi-Oh! 5D's World Championship 2011: Over the Nexus, where they can be traded for special items, including Academia Disks, other outfits, and even Kalin Kessler's Duel Runner, Giganto L. They can be found by investigating certain locations in Story Mode, or earned after beating a new opponent in the Free Duel mode.
In Yu-Gi-Oh! Duel Links Star Chips were used as a currency during the Welcome to Toon World! event, and were used to Duel Maximillion Pegasus. After the event ended, unspent Star Chips were converted to Gold.