I like the concept of the civ!
They add a new playstyle and variety to the game.
But from my playing experience and what I saw in other games,
they lack economic upgrades, my suggestions are:
Give them the buffed berry bushes from Abbassid and Dehli, because they can’t gather the meat from a boar, that would help in some cases with bad map spawns.
The Twin Minaret Medrese, spawns 4 berry bushes that can be gatherd 50% faster, with 5 villager, with gather upgrades 4 villagers can continuously farm these, that is an boost of 2 - 2 1/2 villagers early on, but since they have nothing else and this tech does not scale well later on, it is more an one-time thing.
Same goes for the other landmark “Twin Minmaret Medrese: It spawns with 2 trader gatherd and they collect 28gold / min each, with a capacity of 6”. That is 168 gold / min total. This is equivalent to 4 villager farming gold, but you need also to invest into 4 additional traders with a total cost of 480 resources. There I see the problem, a 2. or 3. tc can produce longterm and cost 700 resources total, so just 220 more and should be favored before adding additional traders to the landmark. But this landmark has longterm value, since gold can become an issue later on.
I think the civ is not figured out yet to its full potential, but executing a 2. TC is for other civs easier, because they have some general economic advantages or bigger early savings and there ottomans got nothing really for them.
I would change the berry bushes capacity on the landmark from 175, to 250. It will boost the feudal of ottomans where they need it the most and later on it’s not a big deal, since farming and food are basically free.
The 2. Landmark is not bad overall, if I would buff it, then just by gold / min. I think the main issue is that players focus on it too early.
Buff: “Anatolian Hills” spawns 8 sheep at your landmark, that can be gathered 10% faster:
Change to: Spawn 8 sheep and increase the gathering of food by 10% for all food sources.
Change: “Trade Bags: Increase the Gold traders collect by 40%” To “Golden Age: Increase the gold traders collect by 30% and gathering rate of gold by 10%”
Buff the T4 Landmark “Instanbul Observatory, The Istanbul observatory increases the bonus to +60% of all military production”
By default it is already +40% at Age 4, so the landmark just adds another 20% for a t4 landmark …
then a single vizier points grants you another +25%, that is better then a T4 landmark.
I would first increase the production bonus per age to 30%, 40%, 50%. The T4 landmark should be buffed to +40% on top of it, the vizer point adding another 25%, you are on 125% production bonus in the influence.
Max speed now is 85% and it feels slow over all ages at its current state.
In the late game you usually produce from 20+ production buildings and other civs have stronger economic advantages that allow them to have fewer villagers while maintaining a constant production of army.
I think the janissary needs a little buff, while they counter efficiently cav, that could be also done cost effectively with spears, their dps for 160 resources is lacking. Other civs handcannoneers are performing well across the board it does not matter what they shoot at, they are just an overall better choice per pop space.