Final fantasy 7 took me 85 hours to beat first time but if u count online then Cod4 easily have over 30 days.

Mount & Blade, it just goes on and on...

Single-player with just one playthrough was Persona 3 clocking in at like 80 hours. I have 300 hours across all playthroughs on P3 FES.

My longest time spent on one game was probably Everquest for the PS2. I spent almost everyday on that game for hours for over 4 years. I probably had over 1,000 hours easy on that game.

Mine was FFXII too. Over 120 hours in.

Pokémon comes close too. All of them are between 80-120 hours.

I went 58 consecutive hours on Pac-man in a last man standing competition to win a Commodore 128.

AOE - Played it when it came out and I'm still playing it to this day with my family sometimes twice or three times a week

Final fantasy XI and World of warcraft.

Now when you say longest... do you mean just to beat the main story or how much time you've spent on it???

Just to beat the story: FFXII

Time spent: Pokemon Crystal - Around 200 Hours

People where I live think GTA games are the longest thing around... but then that's really all they ever wanna play.... that and sports.... I actually finished GTA4 in 13 hours when I was trying to get the Liberty City Minute Trophy, XD. I think people find GTA long because they spend too much time running around just killing XD. [VC was pretty long though]

Guild wars: 2000+ hours. Otherwise FFX at 120 jours.

EDIT: Pokemon Pearl 200+hours already and I am not yet finish with the game. I am still not yet done with the Pokemon league. Level-grinding.