Three have been guessed, two remain. Here's a second hint for those;
8: Not broccoli, but llama's.
Hint 2: They walk around the landscape, there's news items about them, there's even a cheat-code that turns your advisors into llama's!
6: Though it's not explicitly mentioned anywhere, I'm sure each game in this series is based on a certain real-world country. It's not necessarily why I like it so much, but because of the 'year', the architecture of the buildings and the spice-trading theme I'm sure this one secretly references my home country.
Hint 2: Also, the digits of the years in these games's titles always add up to '9'.