I've found myself basically never building unique improvements. Besides Stepwells, they feel weak compared to basic improvements. This mod aims
to fix that, making them a civilization defining trait.

Improvements (v1.2):
============
(all yields listed are what's added to the base)
Ziggurat +1 culture, +0.5 Housing
(base 2 science, 1 culture river adj, 1 culture natural history)
Stepwell +1 faith
(base 1 food, 1 housing, 1 faith holy site adj, 1 food farm adj, 1 faith
feudalism, 1 housing sanitation, 1 food professional sports)
Sphinx +1 faith, +1 culture, +1 food on floodplains
(base 1 faith, 1 culture, 2 faith wonder adj, 1 culture natural history)
Mission +1 science, +0.5 Housing, +1 faith, -1 faith other continent, +1 gold with exploration, +1 gold with colonialism
(base 1 faith, 2 faith other continent, 1 science campus adj, +2 science cultural heritage)
Kurgan +1 gold, +1 culture, +1 faith with Divine Right, +1 culture with humanism, can no longer be built next to each other (a bit
of lore here)
(base 1 faith, 1 gold, 1 faith pasture adj, 1 gold guilds/capitalism)
Colossal head +1 faith
(base 2 faith, 0.5 faith rainforest/wood adj, 1 culture humanism)
Château +1 Culture, +1 Housing, no longer requires a river, can't be built next to each other
(base 1 culture, 2 culture wonder adj, 1 gold luxury adj)
Great Wall +2 gold, +1/3 Housing
(base 1 gold adj, 1 culture adj)
Farms can now be built on Tundra with Civil Service.
Quarry +1 gold