Two years ago I started developing a Mobile Endless Runner as a summer project. Although I never finished the project, I am rewriting it from scratch as I have learnt so much more since I created the original project.
In the game, you are a cookie rolling down a hill. You must pick up cookie dough which acts as health packs, and must avoid milk puddles or kegs which act as health removal. Increasing in health means the player is larger in size but slower, meaning traps are easier to avoid, while being lower in hp (health points) makes you smaller but also faster, which means traps are harder to avoid.
(Prototype Sound effects from freesound.org)