I have played few (actually three) times since their Unique Ability of being able to settle in mountain implemented. I'm a Prince player so I'm not confident enough to make a statement that satisfy higher difficulties player, but I hope my experience playing as Inca can give a little insight in how playing Inca feels like. All three of the UU, UB and UA made me interested in playing as Inca, but mainly because I can settle in mountains, it's a very cool UA.
As a side note, I always play in standard speed, huge map, 8 players (late-game constant CTD always happens with more than 8 players in my 2GB of DDR2 RAM) and always wanted to have many cities which made me 100% pick Progress. Nevertheless, here are some aspect that I wanted to share about Inca:
- Because the unique building is a unique improvements, I consider Inca is not that good towards great persons generation simply because you need more of your citizen in the field, working the terrace farm. So, any kind of buff to improvement (like the one in Authority ideology, I forgot the name) is appreciated. And because terrace farm also increase the amount of food from farm, you can pretty much spam farm everywhere, making Cathedral? (religious building that provides 1 gold to farm) more valuable. It doesn't mean that Inca sucks ass at generating great person, because you can still allocates some of your citizen to great person generation while new citizen will be born faster in respect to other civilization.
-Because of starting bias of mountains coupled with slinger as unique units, you have very good defense. It means an extra advantage in war times to harass and kill your warmonger neighbor units. It happened to me once, my neighbor declared war on me so I made sure to have plenty of slingers. He failed to take any cities while pumping up units after units. I rejected peace offers multiple times, making sure that he made more units, which in turn, giving me experienced bunch of slingers and, in respectable amount, stagnate his city development. Maybe this is what they called "turtling" in RPG? Making a defensive postures that successfully repel any attacks and wasted his resource. You can also combined with policies or religious tenet that rewards you something when you kill units, making sure that you earn more at war times.
- Regarding pantheon and religion, most of the times I pick the one that will give me the most faith per turn. Playing as Inca, I pick the one that gives faith from mountains and natural wonder or the one that gives faith from mines in a hill with resource. For religion, the nature of Inca is having a high number of food production so I pick Diligence? (the one that gives you instant yield everytime citizen is born), or if there are plenty of plains or grasslands, Cathedral for the farm.
- Regarding Social policy, I'm actually confused. I think Progress is the most beneficial because of instant yield every time citizen is born. After that I don't have clear argument towards any social policy other than situational condition. I hope someone can help me making a clear judgement in choosing a specific social policy branch.
This is some of my thoughts regarding Inca. The strong point of Inca is the heavy food generation and access to otherwise unavailable extra resource for other civilization in the form of gold and food from mountain. I hope it will encourage some people to try this fun civilization!