Spore is more "intelligent design" than evolution. Though I suppose what you're describing is too, Kwaad, but in a little different way.
Honestly, there's a lot of ideas out there that intrigue me... Thing is, its easy to come up with a really high concept, and hard to imagine how it would be implemented or if and how it would be enjoyable...
One thing I'm really interested in is player-created content, but I'd like to see something based off creating an experience through the totality of player-contribution, instead of creating a giant garbage heap with no starting point like YouTube... For example, instead of taking the content and ranking it by popularity like in LittleBigPlanet, what if those same levels were presented as an endless and endlessly variable platformer... You play through levels grouped thematically into "worlds" with increasing difficulty, and are ranked by "how far in the game" you go. Get rid of a big centralized community. Massively single player, I suppose.
How about a game where every person gets to simply build on a plot of land... With unlimited resources... Collectively creating a city, which you can then explore. But you're able to save your designs, and move to a new plot... And additionally if someone leaves their plot untouched for awhile, they get kicked out and someone else comes in... So that the city is always full of life, and endlessly variable...
Or it could be goal-oriented. Instead of a big, endless community, which would just fall apart and be unpolicable... Its like you're building the tower of Babel... You're thrown in with others each with plots of land, and you have to work together, building upwards... trying to reach heaven... Each level gets harder, with more people involved, building to a higher heaven, and of course the wrath of god starts destroying your city... Levels start out taking a half-hour, with only 5 or 8 people, and progress to become weeks-long projects with hundreds... To progress individually, there would maybe be more requirements then simply your team making it...
Like I said, easy to come up with high concepts, hard to imagine how they'd ever actually be implemented...
"[Our former customers] are unable to find software which they WANT to play."
"The way to solve this problem lies in how to communicate what kind of games [they CAN play]."
Satoru Iwata, Nintendo President. Only slightly paraphrased.
