Games, as an industry, have a lot of overlap with film. One of those overlaps is that it's still an industry where one person, with the right idea and (depending on the idea) the willingness to invest the ungodly amount of time to see it through, can put something out there that competes with the big teams and big budgets.

Sometimes, the idea hits so hard that you don't even need the time investment. Notch got Minecraft from version alpha to version 1 in 2 years. That one was lightning in a bottle; unlikely to be reproducible consistently.