I know it is a point of contention, but I'm with pineappledan on this : having a chariot without the "rough terrain penalty" is bizarre, and it offers an interesting counter-balance to the brute strength of this unit (block the unit against rough terrain, and attack it with ranged units, since Fury of Nergal partially counters flanking bonus). In front-line combat, a unit with Fury of Nergal can tip the scale (suppressing the Horse cost would allow making such a frontline, and would recreate the "Assyrian chariot core").
I've had Incan units with Altitude training once : my mountains had become a highway.
I like the idea of a movement-based scout, but I don't like the tambo system (it is a watered-down version of what the Immortal has). Why not replace it with some infrastructure (the unit could build roads very quickly, like a Worker with Progress and the Pyramids) ?
I was thinking about an Observatory replacement (it would imper with the Rationalism branch, but nothing stops us from adding a bonus to this UB to the policy normaly allowing its construction) : it would make the Incan UC a little more spread out, and would still be in harmony with the food/science/mountain theme of the civ (and we have no Observatory replacement)
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I like the idea (tests will need to be done to see if this isn't too much though), but the YKM name is too complicated.

Since the Dhanurvidya is a martial art, why not replacing the YKM by this name, and make the faith promotion the same as for the "Bogurodzica" of the Polish Pancerny (in that case, we should replace the name by some thing like "Epic", as a reference to the fact that Mythology is made up of countless legends).
I think the Turtle ship should really be a Galleass replacement and not a Caravel one : its main weapon was its frontal canon, it was manoeuverable but wasn't made to allow deep-sea travel (and forbidding Korea to travel through seas with their Caravel would be a real downside).
Here is what I would more like to see
Geobukseon (Galleass)
Unlocked at Machinery instead of Guilds
Cost : 200 Production (instead of 175)
18 CP (instead of 12) / 24 RCP (instead of 22)
Has the "Deck spikes" promotion (+33 % CS when attacked in melee) (NL) => so it would be like attacking a Caravel to attack this monster (24 CS)
Has the "Blind ship" promotion (when attacking naval units, attacks in melee before attacking in range) (L) => the opposite of the "Spear throw" of the Impi, it would be a reference to how Geobukseon were used to ram against enemy ships before delivering a salvo of fire, and would make it a killer against other ranged ships ; in terms of animation, it would simply be a double fire animation
Cannot move after attacking (L)
=> This ship would be the naval equivalent of the Naga-Malla : it would try to stuck to enemy ships and thanks to its ZOC and its "Deck spikes" promotion, would absorb fire while delivering powerful punches when needed. A polyvalent but expensive ship acting as a spearhead or as a shield.
I don't know what to think about this unit : the Maya are science-focused enough with their UA (demanding you to rush Mathematics) and their UI. The "K'atun Ahaw" will be hard to code, and, at the end, it simply gives +20 % CS to the unit (a bland bonus in disguise unfortunately, contrary to the one the Kibitium has, since it doesn't have a hard cap ; making a unit stronger simply for existing isn't a good decision to me). For the Goody huts bonus, it looks like a watered-down version of the Shoshone UA (a bit more yield at random is less powerful than less but controlled bonus)... I don't think this idea is good (sorry for that)...
I like this a lot, but what 3d model will you use ?
I really don't like actual Etemenanki picture from regalmanemperor. I want to use
this instead. Do you know how it is called in game and what atlas doeas it come from?
This picture is good (although inaccurate). The problem is that it is already used for a Founder religious building...