approximately 600 hours into starhawk

Football Manager 2011

Over 8 days

I think I had over 2000 hours of osu! logged on to my Xfire account when I stopped using Xfire. Since then, I've played osu! a ton more and it probably clocks somewhere between 2000 and 3000 hours. It's such a time sink...

Everquest: 4 years. 3 to 15 hours per day.
I was living alone at the time. Get home from work, order pizza, start EQ, watch TV while playing until 1 am, pay $160 phone bill at the end of each month. (dial up internet the first year)

1) Quake 3 Arena: 15 years. Still on.
2) Unreal Tournament: 14.5 years. Still on.
3) Duke Nukem 3D: 14 years. Still on.
4) Half-Life 1: 12 years. Still on.
5) Half-Life 2: 10 years. Still on.
6) World of Warcraft: 4 years. Started from 2006 to 2010 ended.

There are only two games I can really say for sure, since they both keep real-time records. World of Warcraft comes in at number two, with 433 days, 22 hours, 34 minutes, 54 seconds. Number 1, by a frankly unbeatable margin is Realmsmud, a text based RPG made back in 1991, that I played from high school on...that character has (no joke) 2700 days, 11 hours, 27 minutes, played time.

Darth Mornelithe Dark Lord of the Sith

Name  : Mornelithe          Race  : half_troll

Gender: Male                Age   : 2700 d 11 h 27 m

Class : monk                Level : 99

Class2: priest              Level2: 76

    He is logged on.  Idle: 0

Oh thats easy.

RuneScape

Main game - 387 days played time (No longer play; Quit in 2012)

Old School RS - 65 days played time (Actively playing)

Actually together with the $15 a month subscription and twice yearly expansions it still came out cheaper... Before I got edicted to EQ I bought at least 5 console and/or pc games a month, which were all full price back then. Back in the day when expansions were still real expansions, Ruins of Kunark, Scars of Velious, Shadows of Luclin, Planes of Power, that was adding content. I switched to WoW though at the 8th expansion, there are 21 now... The game truly lives up to its name.

Team Fortress 2, have about 1500 hours put into it

GTA V - 4 days, 3 hours = 99 hours
GTA Online - 31 days, 22 hours = 766 hours and counting
MGS Peace Walker - 268 hours