There's a lot of tips there that are applicable to your project. I agree with the above comments as well that the story needs work. When writing a pitch, try the following format:
- What if Mars was not always a desert?
- The fact is: it wasn't Mars was destroyed 50,000 years ago when it's human population destroyed the ecosystem and stripped it of resources.
- Now you have the chance to go back in time and save the planet and it's people from extinction in a massive, open MMORPG.
- Act now to make this game a reality.