Control a Fly and reproduce, and reproduce, and reproduce. The more you reproduce, the better you are at being a fly pimp.
I made this game for my genetics class originally. Using simple genetics, there is a 50% possibility of the red eye mutation with the first fly, and so on.
Reproducing with a white eyed fly will always yield a white eyed fly, while reproducing with a red eyed fly will yield a 50% chance of white eyes.
Simple right? Happy pimping!