I'd like to see a Fallout game based around the actual transition from pre-apocalyptic post-apocalyptic.
you know, get a taste of the usual comforts of America in the era; then witness it all crumble and be one of the many few who have survived the bombs.
You go out and try to find if your loved ones are still alive, help others with the new destroyed nation, and find the strange new creatures that have mutated from the fallout.

but I can only dream