DrYaboll: You could also check out Neo Scavenger, its a roguelike-RPG in a post apocaliptic setting, heavy on the survival elements.

Its not on GOG though, and its not yet completed, but if you want to play a hardcore survival game set in post apocalypse, try it. You have to eat, sleep, drink, hide your tracks, you can craft stuff, track enemies etc etc etc

Its a really cool game - though not exactly like Fallout, it takes a different approach to the subject.