Thousands of years ago, a new era was beginning for humankind. The nomadic hunter-gatherers who had laboriously earned their place on Earth organized into small groups, differentiating social roles, building the first settlements, and initiating a great revolution. Scientists call this period "Mesolithic", and this game talks about those people.

In MESOS, you are the leader of an ancient tribe, and as such, your role is to nurture the growth of your tribe by adding new members, ensuring its sustenance, constructing buildings, and addressing unfolding events. Each round, you must place your totem pawn on the offer track, then following the pawns' order on the track, you will acquire character or building cards and add them to your tribe. Each card has specific effects and may earn prestige points (PP) as you construct specialized buildings and prepare wisely for the events you will face.