Ooh, there should be a simple crafting system... Think about it, you could craft basic components with stone, wood and metal. Stone could convert to be knappped and chisled into arrowheads, spearheads, mortars and pestles, ect. Wood could be used to make bows, weave into weak shields,ect. And most metal could be salvaged and rusty, and can be used for metal blades, arrowheads, and homemade guns once you have the know-how.