Way back when, I was gaming on a Nintendo 64, proving myself to be quite the competition to my mom in Mario Kart. Then, Golden Eye caught a bit of my fancy (but I could hardly play without cheat codes), narrowing my aim of video games to shooters. In congress the PlayStation 2, and the huge amount of games I played on that. Here's the important part: PC gaming. Somehow, I had convinced my dad to get my first M Rated game (and I was barely what.. 11?). Halo: Combat Evolved.
Hours. And hours. Quite a lot of my free time, actually. Then I started playing multiplayer without my parents knowing, typing as fast as I could to socialize while shooting people's pixelated faces in Blood Gulch, and all the other maps.
Then my cousins got Halo 2 for the original Xbox, and that's how I spent my summers.
When the 360 came out with Halo 3, my parents didn't wanna drop the money to get me my own console, so I started working as hard as I could. Come my birthday that year, I had my own, and I wouldn't stop playing on weekends from the time I got home Friday afternoon to Sunday night's bedtime.
Halo's been there since a young age; I taught my sister and brother-in-law how to play, and now my niece is banned after Cortana. I think I've succeeded.
I guess it boils down to being an antisocial kid that finally found an outlet for my frustration, and a window to actually socialize. I've met plenty of friends, lost a few, and barely managed to keep my room clean enough for my parent's standards.
But, to me, it doesn't boil down to a reason or a specific appeal. It's been there throughout my teenage years, and now that I'm basically a young adult, I can't just leave it behind.