My idea is about introducing culture types and calculating difference between each type and player in trade to calculating gold and science bonus. Gold and science bonus couldn't been less than 1.
How it works? Culture types would been discoverable, like monotheism, polytheism, mathematics, computers, writing, television, etc. By building special building in city, this city will generate culture points of exact type or of each type. These points are added globally per player. When establish trade routes, culture points for each player inside treatment (2 players) are substracted and summarized/added to calculate trade factor. If some result are less than 0, then it doesn't take place in addition.
Why this? Imagine some player are in the same culture region, so these players have similar culture, because it have similar technologies. When conquering, we could get technologies, so we have more familiar cultures. Fact is culture could get impact on trade and we will get more bonus from trading with another player than or foreigners.
Explanation:
Imagine one civilization research technology like pottery, so it makes pots. It produce pots for many years and met civilization without this technology, so imagine, how big should been impact from cultural difference. Because, in real world, wares from civilization A should helps in researching poetry to civilization B, it should also gets bonus from cultural difference to science. Simple and very like in real world.
The same impact should have technologies like math and religions, etc.
University should also produce culture for each type, if it's researched.
What do you think about this idea?
Culture points types/difference
Re: Culture points types/difference
I don't know much about ware types in Freeciv, but maybe connect both ideas? Player will select ware/culture type to trade.