> I feel like research and technology fits under interesting world in that it provides depth to the world and a progression in terms of production.
By "Interesting World" I mean the terrain and inhabitants of the world, thinks like Maskling tribes that the player can interact with. Research doesn't really fit that role. Research in games is typically used to control the increase of complexity of the game and to provide a sense of progression. Consider Civilization, the early game has a lot fewer options than the late game. As research progresses it unlocks more tools for the player, spacing them out to prevent overloading.
> my biggest near term desire for this game is more economic depth
That should come with the Happiness and Morale, with the addition of luxury goods to keep large cities happy. Tin wouldn't be that hard to add, actually, most of the groundwork for it was added with Copper Ore.
> I think your current focus should be on breadth instead of depth
This talk on indie game development has an interesting point on features, think of them as an inverted pyramid. A narrow foundation supporting a broad top. Work from the bottom up with a tight set of core features supporting larger and larger features on top of it. It's a risk mitigation strategy, so even if a project ends prematurely there's still a workable core to it.
There is also this interesting examination of complexity and depth. I think a key part of Bronze Age's appeal is that it's kind of like Dwarf Fortress, but not nearly as complex. That lack of complexity allows the player to manage multiple settlements without getting overwhelmed, and I'd like to build upon that. My plans for morale build upon the core mechanics of placing buildings and managing resource creation, while also reinforcing the need for multiple settlements (to acquire luxuries).
There's also a deeper technical problem. Some of the really interesting possibilities of game set in this era aren't well served by Bronze Age as it is now. I like the culture mechanics that Stellaris has, where the player can shape and evolve their empire throughout the game. I think something like that would fit really well with a game set at the dawn of civilization. Bronze Age as it is, however, is held back by the core simulation of the entire population as individuals. Some really neat possibilities could be opened up by changing the scale rather dramatically, but such a drastic change might seem more like a sequel than an evolution. I don't want to alienate all of the existing players, especially those who have donated to the project.