A former employee of Naughty Dog revealed some interesting info in an interview about Uncharted's original concept. Apparently it was planned to be a bit more like Lord of the Rings, not the realistic shooter it is today.
Don Poole, former environment modeler for the company, discussed how originally the game was supposed to take place in a "forest world" of sorts where the antagonists lived underground. But as gritty realistic shooters became more and more popular, Sony had Naughty Dog ditch the concept for something more fitting within the demographic. Poole then went on to say that many of the designers preferred the whimsical feel compared to the realism. Understandable as the company is responsible for far out series such as Crash Bandicoot and Jak & Daxter.
Imagine how the Uncharted series would've been though had this original concept won over Sony? Would it still be just as successful?