My last technologies were researched in order to grab certain classical Wonders. My next tech goal is Siege Warfare, in order to conquer Gilgamesh. Siege Warfare requires Iron Working + Chariotry + Ancient Ballistics. I already have Iron Working, and Chariotry doesn't do much for me as I have no Horse resources. So I will put that off until the end and research Ancient Ballistics.
For its part, Ancient Ballistics requires Bronze Working + Construction + Oil Lamps + Ship Building. I have the first two and need the last two. So the first thing I research is Orchards.
The reason for Orchards is that it leads to Fermentation.
Besides allowing me to build Breweries to generate Alcohol resources (bonus happiness!), Fermentation also lets me research Oil Lamps.
Oil Lamps allows the rather interesting Arsonist unit. By itself, the Arsonist is a better city attacker than the Light Swordsmen I can currently build. On the other hand, the Arsonist is classified as a Gunpowder unit, and so it doesn't get the XP bonuses that are accruing to my Melee units. Cuzco could build Combat I + City Raider I Arsonists, but that would have to compete against Combat I + City Raider II Light Swordsmen. Arsonists also don't upgrade until the Renaissance, when they upgrade to Grenadiers.
So Oil Lamps is the third piece. To get the last prerequisite, I have to go all the way back and research Boat Building. Since I've had so much land to colonize up to now, I've completely neglected naval technology, although I did research Trap Fishing when I got all but 1 beaker of it from Carthage, and researched Spearfishing when I needed it for Archery.
I took a screenshot of Gilgamesh's forces in Oporto when I was building up. This is what I'm going to have to take on -- a Bandit Footpad, a Battering Ram, five Deer Riders, a Wardogs, an Axeman, two Tomahawk Throwers, and two Archers. This is why I've been trying to make sure I stay ahead of Gilgamesh in power level.
Boat Building in turn leads to Boat Fishing, and from there we keep getting bigger boats as we learn Sailing and Naval Warfare.
Sailing allows me to build the Shipwright building, which is required for any sailing ship bigger than a Galley. Sometimes it's hard to build these buildings because of the infrastructure requirements. For a Shipwright, you need Wood (from a Lumber Camp), Sails (from a Sail Weaver, which requires Cloth or Leather), and Rope (from a Rope Weaver's Hut, which requires Leather or a Weaver's Hut). Fortunately, I have Wood and Leather, which lets me work up the chain to the Shipwright.
I take a brief digression from playing with boats to research Ancestor Worship, which leads to Stargazing.
A historical popup says that I am seventh in wealth despite having over 3000 gold in my treasury. I suspect this is the result of the AI civs building lots of crime buildings.
I return to the naval technology chain with Seafaring, followed by Ship Building.
I also generate Jean Baptiste Lamarck as my first Great Scientist. This is the first Great Person I have generated with Great Person Points. I have gone through six Great Prophets by researching technologies that spawn religions (Shamanism, Sacrifice Cult, Dualism, Monotheism, Meditation, and Polytheism) and one Great General by combat XP, but this is the first point-generated Great Person.
We are now set to research Ancient Ballistics, which will be in the next update.