Shawnee makes river settlement a genuinely binary choice — cities built along Navigable Rivers thrive under its ability, while cities anywhere else are actively penalized for it.
"Nepekifaki" gives Settlements built adjacent to Navigable Rivers increased Food on River tiles, but Cities not built adjacent to a Navigable River receive less Food than normal — a real trade-off that makes river access a much bigger settling priority than usual.
The Hoceepkileni is a unique Missionary-replacement unit.
The Mawaskawe Skote is a unique Improvement that gains increased Culture for every City-State you're Suzerain of. The associated Wonder, Serpent Mound, adds Science and increases Science and Production on all Unique Improvements; it must be placed on a Grassland tile.