How long is a piece of string? :P

The better question is, how does this game idea sound to you? Would you play your own game once you made it? Besides, execution matters more than genre. I was never fond of platformers, yet there are some I spent a lot of time with, even playing them to the end, because they were just that entertaining. Speaking of which, what flavor of game are you thinking? Because a pixel platformer would feel very different from a Thief-like 3D game, yet still fit the description just as well.