The most replay value?

I am currently in the search for a game that has alot of replay value you, in otherwords will keep me playing for many hours! First of all i would prefer not to pay a monthly fee. However i would enjoy to play the game online every now and again. I also usually play FPS or role-playing games. So my question what game should i pick up?

Thz in advance?

2 games that I am playing now that have a lot of replay value are:

• Hellgate London - a lot of people didnt like this game but I enjoyed it
• Titan Quest - just started playing ti last night, pretty good learning curve but still fun

• Orange Box
• L4D
• Call of Duty 4
• Diablo 2
• Civilization 4
• Baldurs Gate
• Mass Effect
• Morrowind
• Knights of teh old Republic
• Grand Theft Autos

Are you looking for an offline RPG, RTS, etc.. or an online FPS? There are almost endless suggestions but if you can be more specific we can be more helpful.

TF2.

Orange Box and all the mods you can get for the games in it will keep you busy for a long time. Other than that, theres Fallout 3, Oblivion, and Witcher, but they're all single player RPGs.

Mostly looking for a game kind of like WoW that you dont have to pay for! or a Fps!

if your looking for a game like wow id say guildwars, or Dungeons and dragons online(the free version is coming out soon!)