In order: assembled board, initial placements, completed game (6)
I played for all colors, so this playthrough wasn’t the most accurate simulation. Findings are based off my own experiences, and I’ll be as objective as possible.
General Inpressions:
The game played well. I only forgot to account for a few mechanics, however, the times that I did were difficult to correct by backtracking.
The elevation modifiers didn’t have as much of an effect on the gameplay as I had envisioned; they mostly just made it easier for players to improve their production (by expanding their settling sites to colonies).
The Militias and the foreign trade mechanic also came into play less than I'd hoped, but did have a noticeable effect on the game when leveraged.
Since I'm yet to specify a victory point threshold for wins, I decided to stop whenever I felt like the game was starting to drag on. By the time blue scored the 14th victory point, I realized it was time.
Issues:
I forgot to increment the ship token (that sails back and forth between Catan and a foreign island), which once caused me to miss a spending round. This was difficult to backtrack.
The way that elevation is currently set up doesn't have a satisfying enough punishment/reward dynamic.
The cost barrier to engaging in significant trade with the foreign clans makes it a more mid-to-late-game component, but the limitation of only being able to make one 1:1 trade per turn (except during spending rounds, which are few and far between; only one was triggered during the playthrough) prevents players from reaching the higher half of the trade chart. The player that gets far enough to claim Greatest Ambassador pretty much keeps it.
The limitation on moving Militias (you can only move one once per turn, including using it to march against an opponent's building) makes it too easy to block other players from claiming or reclaiming buildings. The Militias basically became a more powerful way to move the Robber.
Brainstormimg:
Instead of spending rounds only triggering when the trade ships land on Catan, they could happen whenever they land on the foreign islands as well, thereby doubling the amount of spending rounds in a given ship's lifecycle. Additionally, instead of limiting a player to one trade per clan per round, I could make the number of trades increase as the player's total number of embassies in play increases. Red has an embassy on the bread clan's island and one in their colony? That player can make two trades with that clan per turn since they have built two embassies globally.
To make elevation more relevant, a resource token system could be implemented in parallel to resource cards, where buildings adjacent to a hex that produces, but that are at a different elevation than said hex, produce tokens, not resources. A simple 2:1 (token : resource) ratio should do the trick. A settlement would produce one token for each adjacent, different-height hex, and cities, in turn, two. In essence, this would mean that if you settle on an intersection, you get half the resources from hexes at the "wrong" elevation. This would stimulate more thoughtfulness, and consequently action, regarding elevation changes. It would certainly slow the game down though, which brings me to point three...
The cost barrier to foreign trade is problematic. It's less of an issue if we presuppose the changes in point one, since those changes make the component more palatable as a mid-to-late-game thing, but I think we can do better. Assume for a moment that all existing interactions with the clans are in increments of two; one grain is equal to two bread, one brick is equal to two pottery, and moving a militia one hex costs two (maybe three) bread/pottery. Our newly added resource tokens (grain and brick tokens specifically) are each equal to one foreign commodity. Finally, we'll reduce the cost of embassies from 2 ore and 1 wool to 1 ore and 1 wool. The result should (hopefully) be as follows: players are able to engage in the foreign trade "arms race" earlier, reach rewards faster, and make more come-from-behind plays, whether they be achieved by using the reward tokens or stealing the Greatest Ambassador tile. In fact, this could help mitigate the problem I felt with the militias, where they were too easy to move (assuming we increase the movement cost to three foreign commodities per hex).
As I hinted at above, I'd like to make the militias slightly more difficult to move, which I think can be achieved easily and simply by removing the ability to move them on a 7 roll. This, paired with the increased cost to move them, would make it possible to justify allowing players to move and attack with a given militia in the same turn.
And now, dear Catan community, I leave it to you to give me your feedback and help me brainstorm as critically as necessary. (I'm looking at you u/Sebby19 😉)