Yu-Gi-Oh! - Gishki Aquamirror # 55 - Hidden Arsenal 5: Steelswarm Invasion - Super Rare. Yu-Gi-Oh! is a strategic trading card game in which players draw from a deck of cards forming a hand and take turns playing cards on a field. Each player has a deck of 40-60 cards, along with an Extra Deck containing up to 15 Fusion, Synchro or Xyz Monster cards. The aim of the game is to use a variety of Monster, Spell and Trap cards to reduce your opponent's Life Points to zero.