One of my designs sounded very much like this. You would be a "bean" from the start. After collecting enough DNA you would be bean with legs that can then jump(this gameplay would be like the chrome dinosaur game). After enough DNA you could choose to go into the water and grow fins(water game play would be like helicopter game), or stay on land and get double jump. If on land you could then eventually choose to get a fly ability (the flying gameplay would be like flappy bird). Finally in each state you could choose to get bigger to break objects, or faster to avoid objects to get to your final evolution. I think its a fun little idea, but didn't want to take the time from my main project.