Linked Game
The Secret Code Interface
The Linked Game is the Second Quest in both The Legend of Zelda: Oracle of Ages and The Legend of Zelda: Oracle of Seasons. Different from the Second Quests in The Legend of Zelda, The Adventure of Link, and The Wind Waker, the player obtains a password after completing the games, which they can then enter to play the second adventure. The codes are different every time.
This is unique to these two Zelda games, as no other games in The Legend of Zelda series have done this so far. Passwords in both Oracle of Ages and Oracle of Seasons are interchangeable, and they both give the player different rewards. One of them is the Master Sword, or L-3 Sword. Bombchus, Magical Ring upgrades, the Biggoron's Sword, and even the Mirror Shield are also upgrades available only in the Linked Game. These passwords can be received by talking to different characters throughout Labrynna, Holodrum, or Subrosia. Link can review these passwords inside the Maku Tree by talk to Farore. He can also enter codes to make different things happen.
After defeating either Onox or Veran in one of the games, the player receives a code. They can then start a new file on the game and enter the code. This begins the Linked Game.