You awake in the darkness and the darkness is all you have ever known.  The warm wet scent of humanity is all around you.  You have no words to express your ignorance.  You have no memory to anchor your experience.  You need no comparison to understand your misery.

You have entered Kingdom Death.  It will be the most brutal campaign you have ever played.  You have nothing, you know nothing.  Your only hope is that you may build a better life for your offspring.  Your bloodline may build a civilization from nothing.  More likely you will all die in squalor and ignorance. 

Things you take for granted that you don't have (but perhaps will one day invent.)

The spoken word, the written word, fire, tool use, magic, a system of measuring time, a system of measuring distance, numbers, math, social norms/customs, history, geography.  (This list is not exhaustive)

Starting race: human only, no variant

Starting Classes: Rogue, barbarian, fighter

Starting Backgrounds: None

Starting Point Buy: 24 points

Starting Equipment:  hahahahahaha NO!

If you have to ask, the answer is no.

Each age of downtime the players may take one bloodline advancement. You may choose a class, background or feat to unlock. To take a class or specialty capable of casting spells you must first unlock that class spell list. (For example unlocking the wizard class spell list would allow you to take wizard as a seperate bloodline advancement. It would also allow you to choose the arcane trickster or eldritch knight specialties without need of an extra advancement being spent. Every spell must be unlocked by spending an age of downtime. 

Also the players will vote on an innovation that affects civilization as a whole. Such as the spoken word. tool use.  Nutrition. Clothing. Hygiene. Etc. 

After tool use is discovered each tool set can be unlocked by spending a bloodline advancement. Each item crafted by that set of tools must be unlocked with an advancement as well. Remember that the finished product will still only be as good as your materials. (A well crafted bone sword is still worse than a poorly crafted steel sword.)