The great thing about an innovative game is that it starts with desire. A person or a development team comes up with an idea for a game no one has seen before, and they want to play it badly enough that they're willing to go through all the risk and work and inordinate hassle required to bring it into being.
Suppose you have an idea for a game, something no one has seen before. There are many forms this could take. It could be a clever piece of software you've been toying with, a graphic style, or a method of telling a story, or a haunting image. It could be an untried subject like haberdashery or whale-watching, or a dream you had (SPACE INVADERS, apocryphally, was based on a dream), or just a strange indescribable ...