I gotta say...Fallout 3 reminds me more of "The Book Of Eli", simply because... 1. The Book Of Eli's setting is almost an exact copy of the Fallout 3 setting. Wasteland. Post-Apocalyptic, and merky. 2. Eli is seen as a lone-wanderer type person, just as Fallout 3's main protagonist is the Lone Wanderer. 3. Both Eli and the Lone Wanderer's motive is to make the Wasteland a better place(Lone Wanderer, with Project Purity and Eli, with reviving the Bible) So out of any movie, i'd have to say that the Book Of Eli, is the most similar movie, out there to Fallout 3. Honorable mentions to both, I Am Legend & Road Warriorr, too.
The Book of Eli is post-apocalyptic and involves a lone wanderer, but the comparisons stop there, imo.
Eli has a singular purpose and conviction. I'm not sure how the same can be said of the LW. Not only does the player dictate the morality of the LW, but what little characterization the writing provides seems to indicate an individual who is confused and in search of answers. Everything the LW does is either a function or byproduct of trying to find those answers. As a character, the LW seems to be "going with the flow" and very malleable from a moral standpoint. Saying the LW is trying to make the wasteland better is very presumptuous. The LW may be trying to simply find answers, gain his/her father's approval, get revenge on his father for abandoning him/her or simply serve his/her own ambitions.
The LW didn't exit Vault 101 thinking "I'm going to make the wasteland better", he/she came out wondering "wth is going on and wth am I going to do?" Sure, the LW was intent on finding Dad, but what that meant from a moral standpoint and what the ramifications would be was totally unclear in the early stages of the game.
Really, it's too bad the game wasn't better written, because the LW is perhaps the most malleable of all the Fallout protagonists. With more options it would have made for great rp.
And let's be honest here, a LW-type in a wasteland setting is hardly a unique premise. Those are very loose criteria for drawing comparisons.