Best storylines in a game series

[Immortal Goat]

I can't balieve that only one person mentioned the Legacy of Kain series. The story is so grandiose, and the plot a deep and engaging. By the end of Soul Reaver 2, I didn't know what the hell was going on, who was on my side, and who I could trust, if anyone. MGS is a great story as well, but I think that Deus Ex bests them all. That was one deep storyline, and what made it the best was that at the end, you could actually choose who you trusted the most and follow their lead. Now THAT is open-ended gameplay at its best.