Ideas and all that

For my second project I have been told to come up with a concept of an app game for iPhone/iPad etc so I thought of a few styles; a platform game (which other students would be doing), a drawing based adventure game or one involving animals and creatures (similar to pokemon and digimon so that one was a no). In the end the drawing game sounded more unique so I started to come up with a character.

Here he is (with alternate colour schemes too) he has yet to be named and my idea is that you are the green draggy going around saving your dragon buddies (colour schemes) with the power of drawing!
Ideas of doing this are possibly drawing a shape on screen and an ability or attack would be peformed depending on the drawn shape (eg, drawing an arrow shoots out an arrow, drawing a line enables you to cross large gaps)

I also had the idea that you have limited graphite - so you'd need to gather sharpeners to sharpen your pencil and refuel your doodle power.
I found it hard to navigate through the app store so I couldn't find any drawing games for the iPhone. This has made it difficult to find out what is popular in a drawing based app, however, I have a strong feeling about my concept as it differs from a lot of ideas my fellow students have come up with.