Probably one of these five games:
Super Smash Bros Melee: I've calculated about 600 Hours on my GC, 300 on friends and probably another 100 on Misc systems. About 1000 hours.
Counter-Strike: Unknown amount of hours between my system, friends systems and LAN centers. I'm estimating about 1000 hours.
Sim City 3000 Unlimited: I've spent hundreds of hours on all the Sim City games. But this one probably beats them all. I'll never know how much but its calculated in months, not hours.
Ragnarok Online: I can't even begin to imagine how much of my life I wasted on thisd game. All I can say is, it was practically all my friend and I played from 2001-2003.
Pokemon Emerald: My game file says 450 hours. But it hasn't seemed to add any new hours for a long time. I'm estimating probably 600 or more hours.
Six upcoming games you should look into:
