I guess that would be Pokémon Gold. It was the first "complex" game I ever played. Up until then, I had only played 2D platforming experiences like Mario were you went from left to right pressing A to jump and B to ocasionally throw some fireballs. But this was an RPG. It had tons of text for a 7 year old like me, many "complex" mechanics both in battles and outside of them, puzzles, an interconnected world filled with things to do. It was so different than anything I played before. It was even overwhelming at times. I mean, I constantly got stuck even with very basic stuff (It took me days to even get the Pokédex xD). But with time, I learned to play and I end up loving the game. I put almost 500 hours on it. I became a Pokémon fan. And from that point on, you could make a timeline of my entire life using the next Pokémon main games as a reference in time xD
Thanks to Pokémon, I became confident trying new games. When my parents got me my GBA SP, I discovered Metroid Fusion and Zero Mission, Golden Sun and its sequel The Lost Age, The Legend of Zelda: Minish Cap... and in turn, I became a fan of all those series. I became a Nintendo fan.
So... yeah, Pokémon Gold started everything. Not only made me a Nintendo fan, but it marked the path for how my gaming journey would be. If it weren't for Pokémon, I may have not be interested in videogames today as much as I do. Now I'm not only a Nintendo fan, but an enthusiast of videogames in general.
