The Legend of Zelda: Link's Awakening

Link's Awakening was a Zelda game released for the original Game Boy, and later remade for the Game Boy Color. It is widely considered to be one of the best handheld games ever made and one of the best Zelda games. It introduced great concepts to the series like the ability to jump and the ability to have multiple items equipped at once, while introducing some damn owl that everyone got sick of seeing about two minutes into the game. You really thought Navi was annoying?

Instead of sticking you with a sword button, Link's Awakening allowed you to have any two items at the ready. You could use two specific items together to do things that were otherwise impossible, like jumping over large gaps and shooting bomb arrows.

Link's Awakening also had the first instance of morality in a Zelda game, giving you the ability to steal items from the shop. Everyone will call you a THIEF if you do. But really, it's the storekeeper's fault for charging 980 rupees for a Bow and Arrow set. Did all the random Moblins have to pay that much?