Longest games i have played are the Gran Turismo series. The Endurance Races take ages.

well

i never understood how not to die at the end(?) of Doom

Longest game o played was Tales of Symphonia, Hardest was the The Legend of Zelda(nes)

Hardest game ever played has to be friggin BATTLETOADS. Bad memories!!!
I have to agree with Devilstation when I say Gran Turismo as my longest.

I never played one that has both but longest is Star Ocean 3 (over 90 hours for my first save file) and hardest TMNT on Nes... I played it on the original NES when I was little and I never passed it. It's an unforgiving game that made me so frustrated I just stopped thinking I could beat it.

Longest was FF X, I don't know about hardest, maybe the original Pursuit Force or Killzone liberation (it would be on hard)

Thousand arms for PSX...I stuck in the same spot for 2 years (and I am dead serious). Finnaly I discovered gamefaqs, and finished that game.

About the hardest...hm...FF VII.

Longest: Super Mario World
Hardest: Super Mario Bros 3, I never finish it

Longest: WoW