Something new in your everyday hunter-gatherer routine: where did this strange edifice come from? Dare you enter and explore the secrets of this... thing, or do you try to face your enemies? Like you have a choice.
Starting as an early anthropoid, you find a mysterious stone structure that leads you to three crucial moments in the development of humanity, from tool use to the domestication of animals. Good prose, reflective of differing perceptions at the various levels of development.