Because of the amount of art required by this project, we will be requesting extensions to the initial round (typically 4 days) and the final round (typically 3 days). 99designs has already assured us that this would not be a problem.
The tentative extension amounts will be a total of 14 days for the first round (will end on October 2nd around 12:00pm EST), and 7-14 days for the final round. I'll post the actual end date for the final round when we enter the final round.
It is important to inform you of this so that you can have time to really plan out your art, and you can also submit early/rough sketches and such if you desire--we can look them over to gauge if it looks like a good direction to go with the art. We can iterate your art ideas like this if you want so that you can be sure to focus your efforts in a positive direction. This is not required, but we wanted to offer this option for those that would wish to take advantage of it. However, in order to go into the final round, at least a fair amount of color must be added so that we can see how the color will look on a finished product.
The previous paragraph makes it sound like we have certain art in mind. We don't. If we were to check your sketches, we would only be looking for the necessities discussed in the attached document. The rest of the creativity with the art is up to you. We are not artists, and we know this. We want you to be free with your creations, as long as the necessities are satisfied.
We will occasionally show your work to various groups of people in our target audience for this game, and it will be their aggregate votes that will ultimately decide if your art is what the game needs. But this will not happen until later in the contest: probably just before the final round, and another time just before a winner is picked.