I feel that feature wise the game is basically complete. From here it is about refining the ideas and evaluating them for improvements / changes.
To read up on the progress of the game so far, you can check out the previous developer diaries here.
Most recently I have been trying to update the presentation of the game to make it look more appealing. Right now I am playing around with the challenge award graphics to make them look more interesting. Compare these to the other ones in the gallery and see what you think.
Game looks interesting, but design looks not good.