Watch over your tribe for generations. Help it advance in technology and culture.
In Dawn of Mankind, the people of your clan move along paths, gather resources, have children, create art, discover new methods of doing things...and eventually grow old and die. As your clan goes through these ordeals, you need to pay attention to when your food is going to spoil and where other people might want to go because if they choose the same path you've already trodden, they may inadvertently help you along your way.
You earn points for a variety of things, and whoever has the most points in the end wins.