Civilization II made me a fan of turnbased strategy games.
Age of Empires II made me a fan of real time strategy games.
Shogun: Total War made me a fan of real time tactical strategy games.
Icewind Dale made me a fan of isometric roleplayish games
Star Wars: Knights of the Old Republic made me a fan of third person rpg games.
Fire Emblem: Awakening made me a fan of strategy rpgs.
Fallout made me a fan if turnbased rpgs.
Halo: Combat Evolved made me a fan of first person shooters.
The Legend of Zelda made me a fan of Action Adventures.
Metroid Fusion made me a fan of metroidvania style of games.