The Elder Scrolls IV OBLIVION. I swear, it is my favourite game EVER. I have never got bored with it, i don't know how you can. I have played it for probably 600+ hours and d'you know what? Theres still more to do. Always that new little patch of land to investigate, that new enchanted item to find. Did you know theres a named silver war axe calld ''defiler''? or a named dwarven battle axe called ''naked axe''? I even found fin gleam. Without help. if you know what fin gleam is, you're probably gonna find that hard to beleive, and i respect that.
Did i mention i love argonians? And i mean i LOVE argonians...
A close second would be Fallout 3, another Bethesda game. Played it a little less than oblivion. And i mean a little.
And in terms of waiting for a sequel, Timesplitters. I'm never giving up on that sequel. Ever.