Hmmm....
What are my options for running a Fallout game?
Use the Fallout: Pen-and-Paper RPG rules, which seem to be a literal translation from the computer game, meaning added complexity...
Use d20: Apocalypse:.... But I dislike cancer....
Use a user made Fallout module for GURPS.... maybe....
Or, just modify the Shadowrun rules to work in the setting... strip out magic, metas( or modify for ghouls and mutants), cyberware, the matrix and add in a lot more devastation. Combat drugs will be renamed and uber emphasized... Come up with a bunch of shitty guns... severely restrict starting money... And make bullets even MORE expensive...
I like