Fallout 3. Now thats a non-linear game and there are literally thousands of paths to take.
True, I also pretty much enjoy Fallout 3. Although some events are too random for my taste.
For example, when I was supposed to kill an android on a quest, I found out, that it was in Megaton in Craterside Supply. Then I was just running around Megaton, searching for more clues and suddenly, this random woman pops up from nowhere (literally) and starts asking, why I'm searching for that android, taking the quest in another direction - what wouldn't have happened, if I didn't just randomly walk around the city, practically doing nothing. Maybe I just need to get used to RPGs
Mass Effect has the best story of any shooters.
I would hardly say that. It's not bad, but the story wasn't pulling me in like say, Mafia or Deus Ex. Besides, the whole story is just a ripoff of the Heechee saga from Frederik Pohl, so it's not exactly original either. Only here, the writers didn't work on the backstory and intentions of the Reapers, and simply went with the Hollywood approach: "They're wiping out the entire universe, because...errr...they're EVIL!"