MGS for PS1 forever.
If someone were to do all of the quests in the game there'd have to be at least 2 or 3 different types of runs. Lazarus can be killed on one of the levels in hell...but sometimes he gets his own level. There's Garbad the weak or whatever who is random as well. I think the only ones that are consistent are The Butcher, maybe the skeleton king, that one armor quest, the halls of bone whatever it's called and diablo.