Oblivion, though I might end up getting the PC version....then Gears of War or PD0.
I've never been bothered by the fact that the Elder Scrolls series haven't been made online. Unlike most single player RPGs of late, Bethesda has always managed to include an incredible amount of depth, immersion and content without going online.
Oh, and since this isn't exclusive to launch titles, I'll also include whatever the 2 titles Bioware has in development
Bookmarks