Oh boy, what game should I choose? I bet my avatar has no relation with that game...oh wait.
The World Ends with You is my passionate love, since Square made it near perfect - fun combat, great story, nice graphics and insane replayability(getting all the upgrades+all the items+all pins at max level took me more than 250 hours of play). I'm still angry there's no port of Solo Remix for Android.
Danganronpa gets quite a lot of love from me, as well, since it's like a mix between Ace Attorney and Virtue's Last Reward...but with the best story I have ever seen in a video game.
Other than that, well, I guess Osu! and Flappy Bird, but those are more like manias than true love.