This game design document provides a great summary of the direction behind this game. It includes a specific production check list outlining the tasks the game's developers must complete. This will be incredibly helpful as the team determines the final scope of the game. The concept art is also useful in providing readers with a clear visual of the game's level aesthetic. I also appreciate the how upfront the document is with areas that still need to be worked out and finalized.
One note is that I do not believe the document references any sound effects or music. It will be important to include these in the final product to help enhance vibrant and cartoonish aesthetic.
Wishing you the best as we move forward!