I hope you will try very hard for Chocolate or Cocoa.
I am sure you can find artwork for Chocolate.
It was of major importance as a drink as well as a food, and is another example of something from the New World.
2D graphics like buttons aren't an issue, I can easily make them myself for any resource. The 3D in-game model is the issue, though I could possibly recolour the one I'm using for Coffee.
Coconuts would add variety and fits in well with Polynesia.
Agreed but sadly I've not been able to find any usable 3D graphics that even resemble a coconut palm. The most important crop of Polynesia and South America was the potato though, so at least that's in.
Seals is a possibility for another sea resource.
I have seal graphics (actually sealion, but close enough) but the challenge I have is placing them properly. The graphic is designed for land placement and there is no built in mechanic to place resources only on land next to the ocean. I could instead just place them in coastal tiles (below 45º latitude) but it might look a bit odd as they'd be sitting on the water.
You will probably have to do some rebalancing to avoid making it too easy to get happiness and health with the additional resources available.
That's why I'm thinking of removing the health/happiness you get just for having access to a resource and retaining only the health/happiness you get from buildings like the Granary or Grocer that can use the resource. This should make happiness/health buildings like the Baths more desirable, and possibly even the culture slider.
Fermentation is a very old technology which I suggested you add, which would work well with Barley and Grapes (wine).
I'm leaving the tech tree as is for now (other than adding crosslinks) as it's so time consuming to work on and other aspects of the mod need work first. If I eventually go back and add more techs Fermentation is definitely a strong candidate.
Fruit trees rather than specifically apples might work better, although apples for the artwork would be fine.
I have art for Apples and Lemons that I've not used yet. So I'm thinking Apples, Citrus and Bananas. Or keeping it simple as Fruit and Tropical Fruit (renamed Bananas). Or some combination thereof.
Reason I haven't decided yet is I'm wondering if there isn't some interesting way to make Citrus improve Naval buildings/units.
Iron working did not require coal, at least for the first 1000 or 2000 years it was done.
As you point out, copper and tin for bronze would only work in the game if the tech tree at that stage was stretched out (more techs each costing somewhat less) so that the Bronze age lasted considerably longer.
Yep, and for both these reasons I think I'll just leave it as Copper and Iron, for now at least.
I was thinking that with some buildings some resources could give hammers or coins rather than health or happiness. Perhaps in one or two cases, a combination of building and resource could even give a free great person.
Resources by themselves can give health, happiness, food, production, or commerce. Via buildings I can make resources give health, happiness, a % increase to food/production/commerce or provide power (like coal plant).
Buildings can also provide a free bonus (like Broadway, Hollywood and Rock n Roll do) and this is a mechanic I'd like to explore the possibilities of at a later time. Unfortunately there is no way to make a building consume a resource. Instead they can block a resource being accessed (like National Park), speed up production of the building (like Stone and Marble) or require a resource in order to be built at all (like units).
Any else would require Python coding and thus creating potential AI issues. For 0.9.3 I'm sticking to the available mechanics but in the future I may experiment further.
There are other resources that are used in manufacturing today.
For example:
Rare Earths.
Lithium.
Titanium.
Perhaps some of these could be included for the modern or future era.
I was considering setting up a Aluminium/Titanium dichotomy in the modern era much like the Copper/Iron one in earlier eras. In the interest of getting it finished in a timely manner I decided to leave that idea out of 0.9.3. Even if I don't go with that idea there is definitely some scope for new metals in the modern era.
The other factor I should mention is that there seems to be a 'soft limit' of 48 total resources allowed. Although I think I can add more than this it requires a lot more work and testing to do so and thus I do not want to go over this limit in 0.9.3. Indeed I'd like to leave a couple 'slots' free for now, just in case this limit turns out to be insurmountable.