1. The Legend of Zelda: A Link to the Past (SNES)
The addition of parallel worlds added depth to the zelda universe's gameplay. This game wrote the formula for those later to come with all of its additions. Spin attacks, heart containers, many items, and multiple floor dungeons with more than just staircases to travel between floors all were wonderful features of the huge zelda world. There were so many hidden wonders to discover in this world that exploring was often as fun as the massive dungeons. What really made this game is the unbelievable number of items and upgrades to those items you get throughout the game, some very useful ones which aren't even required to complete the game. Many of these items such as ice and fire rods are sorely missed in other games, which usually have a small subset of the arsenal. There was also a fairly significant amount of story for this game to keep you involved if somehow the gameplay was wearing thin.
Primarily an RPG player but have interest in any game that will make me think.