Yu-Gi-Oh! The Eternal Duelist Soul, also known as Yu-Gi-Oh! Duel Monsters 5: Expert 1 (遊☆戯☆王デュエルモンスターズ5 エキスパート1) is a video game for the Game Boy Advance, and the first game to follow the real OCG/TCG rules. The game is very similar to its English version (Yu-Gi-Oh! The Eternal Duelist Soul) in the story, but different in the graphics and the Booster Packs (The Eternal Duelist Soul uses the same graphic as Yu-Gi-Oh! Worldwide Edition: Stairway to the Destined Duel). Gameplay is similar to standard dueling rules, except that the Side Deck can have less than 15 cards, and is more for convenience of getting to cards for your Deck than switching between duels, as CPU duels are single duels rather than matches (though you will have a match duel against a character every two weeks on a Saturday).
Gameplay
Opponents are arranged in "tiers," with higher tiers unlocked by beating already open tiers. A tier may consist of 4 or 5 duelists. In order to advance, all duelists on a tier must be beaten a certain amount of times before the next level can be unlocked. Beating a tier also unlocks certain in-game events, such as special cards that can only be received by beating that tier.
Another important aspect of the game is the in-game calendar. On certain days of the week (not actual days, as the game does not support a real date function) in game, random events may occur, such as recieving a pack of cards in the mail or being challenged to a Match by an opponent.
This is the first game to include Polymerization as an actual card. It also includes the Egyptian God Cards, though they are completely unusable, as the game considers them illegal.