There wasn't any specific game that made me buy the 3DS. I obtained my first one in 2011 when it was a new system, so I knew there would be a lot of games coming in the future. I was definitely right because the 3DS has an incredible library of games now.
It's really been almost 8 years since I bought the 3DS and I still use it on a daily basis. That is incredible longevity for a gaming console.
i only got mine for pokemon xy. i realized that i should look into more games for it and bought new leaf on a whim a few days later. best impulse purchase i've ever made LOL
I only owned New Leaf (bought at release, along with the 3ds) for years until I had my son and he got into Nintendo characters at 1 and a half years old. We got a bunch of different games and now that he's older the 3DS is his.
There wasn't actually a singular game that made me buy the 3ds. My mother brought it because my original ds broke (and by that I mean the really old ds', like, the ones before the 3ds came around) so I could still play the games that were meant for my old ds and also get some new ones as the games came out for it
New Leaf was going to be my priority, though it wasn't available in the store anymore so I went with Omega Ruby instead. I'm really glad I ended up buying OR though since that really got me into the Pokemon games.
For me, it wasn't a game that made me buy. My old ds lite kicked the bucket and when it happened that the 3ds was already out for a year or two. I thought, why not upgrade so I bought one. Honestly looking at it now, it was one of the best decisions I made. Especially since when I actually got to the store, the worker there tried so hard to make me get a ps vita instead. People can be obnoxious.