What Game best utilizes the concept of "flow" to me?

   I have played a lot of different kinds of games in my life. I would have to say that Oblivion Elder Scrolls 4 Utilizes good "flow". In the game you start out in prison so you can get a chance to learn how to use your abilities, and you also get a mission that you have to complete, but you don't have to complete it right away. You can complete the mission any time you want. You also come across other things you can do, for example; you can join different factions, some factions are Mages Guild, and Fighters Guild, You can also do missions for different Shrines that are all over the land. There is also missions you can do for regular people. While your doing all of these different missions it always brings you back to the main mission and it also gives you a chance to learn new skills and make your character stronger.
                 I think that Oblivion uses good flow because you have to use all of your resources that you find. You have to use a silver, Daedric, or magical weapon to kill a ghost, or Wraith. You have to use your illusion magic to see in the caves if you don't have a torch. In some point you will have to use Conjuration magic to either distract an enemy, or to help you fight. You also have to use your sneak ability a lot during the thieves guild missions. It seems like every object, or resource is used in the game at one point or another.
            I have played the game a lot in the past two years and i'm pretty sure that i haven't found every mission in the game, and i'm pretty sure that i haven't found every object in the game. Oblivion seems to cater to the Explorer, and the achiever. How ever it also has someting for the collector, because you have to find some statues and you can also collect armor and weapons. The game seems to cater to a lot of different players and i think they pull it of nicely because it is hard to create a game that caters to everyone.
               As far as "flow", I think that when i played the game everything seemed to go together like a puzzle. No matter what you did you always came back to the main mission. When you finally complete the mission you can still explore, or finish any mission you haven't completed, and i think that it is good that the game is set up so you can continue to play and explore even after the story ends.