For me, it's the Journeyman Project series, a series of adventure games that I was obsessed with but no one ever seems to mention.
Yes! Journeyman Project Turbo was included with my family's first computer. That was the only game in the series I ever played. Loved it, even though you could beat it in an hour once you knew what to do.
The only game system I had before that was my Game Boy, so a lot of the important games for me were the weird GB cousins to NES/SNES games. Battletoads, Mega Man in Dr. Wily's Revenge, the Super Mario Land trilogy, Link's Awakening, and Final Fantasy Legend II, which I sunk countless hours into but was never able to beat.
I took my Vita to my folks' house to get a few good hours of Persona 4 in. Between today and New Year's, I'm gonna maybe try to finish XCOM and Red Dead Redemption: Undead Nightmare (yeah, I'm behind on that).
As far as stuff I'm actually in the middle of playing: I'm still trying to finish XCOM:EU and Torchlight II, I just started on Dishonored and Persona 4 Golden, and I still need to finish RDR: Undead Nightmare from when I finally started on it back in October.
My backlog of stuff I haven't even touched yet is just dumb, but top priorities to play are Metro 2033, Just Cause 2, Witcher 2 and GTAIV: Ballad of Gay Tony.