Assume that your one Scout can do all the necessary exploration quickly enough, and that your existing troops can hold long enough to get the economy going. All available food will be allocated to producing villagers until you have 15, and then you will produce three more Bowmen, and then you will not produce any more units until you can afford a priest. Your initial villagers grab whatever resources they can see nearby, and that means three villagers collect food, and the rest collect wood. The next two collect food, and the last three head for the shallows, one each. When you find stone, send two villagers to mine it, and likewise for gold.
Your Scout heads to the south corner of the map and then around its edge in a counter-clockwise direction. You quickly find 5 each stone and gold mines. This is enough to get you started. It is all the ore that you will find in safe areas. There is a huge amount of ore on the map, but you will have to fight for it. You will find a huge number of Gazelle on the map, but hunting requires too much micromanagement, and there's no reason to hunt in this scenario.
Don't expect your swordsmen to stand up long in combat. Immediately reinforce each pair in the shallows with one archer and one swordsman, and then one more archer as you produce them. The archers are very important, because they make those groups much more powerful. You need to be a bit concerned about sending your units through unexplored territory, because predators could hurt you, but it turns out that there are no predators in your part of the map.
When your Scout gets to the river, stay on your side. You don't want to provoke an early attack. You find that the three fords are the only access points to your area. Of course, the AI will not be able to use amphibious invasion to cross this river. You could, if you wanted to. You will protect the river fords with a small fleet. It's not initially clear that the river is wide enough that your ships will be able to move along it. You may need to build several docks. Note that the dock itself may come under fire from the other side of the river.
Villagers 13, 14, and 15 start walling off the river fords. Seal them off completely, leaving only one small hole somewhere to let your Scout through, and only temporarily. When that's all done, you will build one Tower behind each wall. You will defend each wall with one Tower and some archers, with one War Galley to help out, and in particular, to deal with attacking siege weapons. You should also have one Cavalry at each ford. You probably don't have enough stone to afford more than three Towers until you secure a second stone deposit.
After your first priest, produce three warships and then three Cavalry and then one more priest. After that, don't produce any more units unless absolutely necessary. The priests and Scout (and one swordsman, ha ha) form your central reserve. All other units are split equally among the three river fords. It may be that producing all these units so early is a waste of resources, but it's better to be safe than sorry.
After producing your second priest, don't spend any more gold. Do the usual low gold routine: research Iron Age, research Coinage, and don't collect any more gold until you have Coinage.
When your walls are nearing completion, it becomes fairly safe to send your Scout across the river. You find that there is a second river parallel to the first one, so that there is a strip of "no-man's-land" between your safe area and Kyushu territory. There is a huge amount of ore in this area. There is also a lot of food, but that doesn't matter, because you have enough wood in your safe area to support farming indefinitely. Kyushu has some Towers here, and probably a few units. You need to secure this entire area for yourself, but you won't do this before the Iron Age. If you fail, and Kyushu starts exploiting the resources, at least you will be able to wipe out all their villagers. Overall, the situation is looking pretty good.
When your Cavalry become available, start raiding the central area with them. The primary targets are enemy catapults, but you also want to break up enemy attacks before they happen. Opposition will be strong, so you need to upgrade your defenses. Produce two more War Galleys and move them to the middle ford. Open a hole in the middle wall and continue raiding via the middle ford.
The Iron Age
If you've done everything correctly, you should enter the Iron Age at about the 25 minute mark. You should have 670 gold left on the ground, but realistically a little bit less. After Coinage, this will be worth a bit more than 835. The most important units to purchase are 2 Phalanxes (180 gold), one catapult (80), and 5 horse archers (260). You also want to upgrade your cavalry size (120) and priest speed (120), for a total of 760 gold. Your 9 cavalry units will be your primary strike arm for the next phase, and you want to improve them as much as you can. Yamato priests are quite weak, and you want to give them some help. Other than that, get every upgrade that doesn't require gold. You should probably get Ballistics as well, because it is cheap and very useful.
You definitely want to get more gold, but this is not realistically possible yet. What you can do is secure a second substantial stone deposit. The stone deposit in the middle of the map, close to the first river, on the Kyushu side of it, is accessible only along the river. You can easily wall the area off completely. Kyushu doesn't even go into the west part of the central strip, so that area is safe anyway. Your troops will dominate the central strip in any case. However, wait until your horse archers have strongly reduced the Kyushu army before claiming this stone.
There is a large deposit of both ores in the far east of the central strip. This area can also be easily secured, because it is only accessible along the bank of the first river, and your troops will completely dominate this area. However, as it turns out, your 5 horse archers will crush all opposition so rapidly that you won't need to produce anything more than what you already have.
When Kyushu is down to just a few units, and cavalry sweeps can't find any more Kyushu units in the field, run into their base and hunt down the remnants. Instead of hunting down all the villagers, you could just shoot at some buildings, and all the villagers will come right to you. Kyushu has a lot of Towers, but doesn't have Ballistics, so you can pretty much run right by them. Your horse archers also outrange the Towers, so you could just blow them up, although it does take some time.
When Kyushu has no units left, you still need to blow up all their undefended buildings. At this point you might as well get some Nuke Troopers and finish the scenario that way.