Today I had a very enjoyable game (not finished yet) as Songhai on Prince, Small size, Continents, Standard speed. 5 AI players and 10 city-states.
I shared my medium sized continent with Pachacuti and 4 city-states.
My first SP choice was unlocking Honor for some awesome culture from Barbarians. That with 3x gold from barb camps is a nice combination. After that I filled out Liberty.
First I decided to build 3 cities for the most ideal city locations near my capital. My first target was actually a militaristic hostile CS north-east, which's name I don't remember anymore, but I unintentionally finished some quests for them, making them my ally for the rest of the game.
So, I decided to take Cape Town, located south-east from my capital, which was hostile too. Capturing was quite easy with some swords, pikes and catapults.
East to Cape Town was located Dublin (which was hostile too, sigh!). I captured it after upgrading my swords to longswords, pikes to musketmen, catas to trebutchets and built a few Mandekalu Cavalries.
The weirdest thing is, that Pachacuti remained Friendly to me even after capturing TWO CITY-STATES! Most civs would go "omgwtfbbq denounce

" about that, but Pachacuti apparently did not!
Maybe that was because earlier in the game I returned his worker.
But. Even if Pachacuti seemed like a good friend, I targeted him next. He kept building a lot of wonders and ignoring his military! The first city I took was Tiwanaku or something. That battle was horrible despite his small military! I lost all my units except for a trebutchet and a 3 hp longsword! Luckily, the city was so damaged I successfully captured it.
To avoid losing anymore units, I made peace with Pachacuti. He gave me 3k gold, so rebuilding my military became significantly easier! And Tiwanaku had the Colossus, so it became my gold city.
During the peace time, I rebuilt my military and sent it to Tiwanaku for fast access to Pachacuti's lands. For my surprise, Pachacuti had built a damn lot of Vanguard units! I was horrified, as I thought that would make my conquest damn harder!
But I must admit that Pachacuti made a very good move there!
Beating his Vanguard units at that point was near impossible, so I decided to wait until I get some Infantry and Artillery. For my luck, he never upgraded his older units even though he was a runaway in tech and culture.
And then the battle for Cusco began. However I would compare it to the battle for Stalingrad. That was so damn slow and almost made me want to end the war for a stalemate. But I succeeded capturing Cusco, and my score jumped from 3rd to 1st! Cusco had around 9 wonders! Thanks for building them for me!
I then began capturing the rest of his cities; they were a lot easier.
My empire ended up with 15 cities (including my own 4 cities and 2 CS), one of them being a one-tile island with Marble I had isolated Pachacuti on after capturing his other cities. He refused to give me anything in the peace deal. When I proposed that he would give his open borders along with the peace, he thought that me giving all of my gold, luxuries and open borders would make it more fair.

He had it coming.
Other fail on Pachacuti's decisions:
He only built 2 Terraces, both of which had only 2 or 1 mountains adjacent. Near Cusco there was this huge mountain range which would have fitted SO MANY Terraces! Most being adjacent to 3 mountain tiles! But instead he chose Villages for them. I might know the cause for this: he probably has a high gold flavor.
Also: I haven't ever built an empire this big in CiV! I like playing tall, but this warmongering game was a lot of fun!