If I had to choose a sister game to Rage then I personally would say Far Cry 3. Not so much in storyline but in a sense of feeling and audience.

Both are FSP, both are open world, both have vehicles, both require you to craft items for aid and both have a similar feel in sense of maturity.

Fallout is nothing like Rage other than both are futuristic set in a post-apocalyptic environment. Mechanics and game play are totally different and Fallout is more about scraping to survive whereas Rage is more about fighting a corrupt authority in an abundant world (like Farcry 3).

Borderlands is similar to Rage although it is set on an alien world and it's ambience and feel is much more comic book style whereas Rage is not. Rage I'd more like Far Cry as it is more serious and real world like.

With this in mind then could the success of the Far Cry carry across to Rage if marketed right? I'm not sure of sales but I get the impression that Far Cry 3 was one of the biggest sellers for it's year. If so, is there anything Rage learn from the Far Cry series such as the massive openness?