Here is the full list of all 12 Oldowan Demo achievements.
Build a boat.
Die.
Plant a tree or crop.
Engage the chickens in combat.
Craft an Oldowan-styled tool.
Smelt your first metal.
All that neck, but not enough peck. Defeat a Moa.
Defend yourself against a Wolf.
Defeat a Mammoth.
Craft an iron tool.
Loot your local body of water.