His "membrane" gives you a sense of the complexity of the struggle for survival. Lead the bacteria by eating their own kind, accumulating biomass to grow more and more. The main goal is to make sure you are not eaten in the process. Over time, gameplay becomes more complex. Compete with other "single-cell organisms" by recoding your score at the online high score table. And remember, Darwin was right, "Survival of the fittest" is the rule!