Place food with your finger/mouse, and watch the cells grow. The rules are simple: The cells will walk around randomly and will eat all food they walk into. Cells start with 8 energy, they loose 1 energy per second, and if the run out of energy, they die and turn into food. A cells can gain energy by eating food. If a cell reaches 13 energy, they will multiply and return to 8 energy.
I was really bored, so I just made this. Inspired by single celled organisms.