Eternal Darkness: Sanity's Requiem had a pretty lame ending. The whole game follows H.P. Lovecraft's premise that mankind is very insignificant in the universe, that we are merely ants at Cthulhu's picnic. Then after a boss battle with the Ancient's pawn, and then the player is forced to change a symbol in a spell to save the world. And no matter how many times I intentionally picked the wrong symbol it wouldn't give me a bad ending.
Don't get me wrong, I loved Eternal Darkness. Maybe it's just me, but it just seemed so out of place.