Hello, everyone.
I apologize in advance for possible mistakes and typos, English is not my native language.
I know, that it is a bit late to post guide like this, but better late, than never.
I also hope that this guide will help you win this match and will save you from most troubles on your way to the Achievement.

This scenario is built around global Victory Point race, in which different groups of civilizations get different bonuses for different achievements. There are 3 groups: europeans, north-africans and sub-saharans. Europeans earn points for discovering artifacts and for longest railroad, north-africans - for GPT amount every turn, and sub-saharans - for culture every turn. In this scenario you play as Boer civilization of sub-saharans and, by default, you should develop your culture. As all sub-saharans, you also get culture for defeating enemy units, which all contribute to your total VP count.
The Africa's interior in this scenario is always randomized, which means that only 2 tiles of land from coast are the same in every game, and everything else is almost completely random. This, and some other aspects, adds several difficulties to both playing this scenario, and following any guide about it:
- it is impossible to tell exactly what to do, to achieve victory; there is always a high degree of randomness, you can never know, whether Ethiopia will get damaged by their constant wars with europeans, or if you will be attacked by Zulus;
- although there are tiles, on which you should found cities, you might get in disadvantageous position because of too random terrain: you might not have enough luxury resources to keep your nation above -10 happiness, you might not have any additional horse source, or tiles, needed to find new cities on will be mountains; this all may require you to restart game several times to get new map
- if you follow strategy, suggested in this walkthrough, you will have no gold at all, and you will have to build everything, calculating carefully your every move to build needed units in time;
- you can't rely on anyone to sell you anything, because you neither have gold, nor good relationship with other nations in this scenario;
- you cannot lose any of your original cities and any of your units, especially at the start of the game; you must prevent damage to your cannons, if possible; you should start training cavalry as soon as possible for city capture.
But there is also a bright side in all this: your units won't be disbanded, no matter how negative your income is.

Most part of south Africa is a flat terrain, which means that you should promote all your units flat terrain type, with exception of cavalry. This way you will be able to hold positions with foreign volunteers, bomb out your enemies with cannons both on land and in the sea, and beat them out of occasional forest or hill tiles with cavalry.
The main course of leveling up must be like this:
foreign volunteer: shock I, cover I, cover II, shock II, medic I, medic II, shock III, march;
cannon: accuracy I, accuracy II, accuracy III, logistics, range, volley, march;
cavalry: drill I, drill II, drill II, march, charge.
Nonetheless, in certain situations it will be better to get some promotions prior to ones listed here. For example, if you have cannon shortage (usually happens at the start, when England have already lost it's cities, but don't want to make peace yet) you might have to get volley promotion instead of following accuracy path to bombard city and capture it.
Also remember: your cannon can travel 2 tiles by road, place itself and shoot once in a single turn.

Good position for properly promoted cannon.

Try to place your cannons on hills, and your soldiers on flat terrain between hills, to stop enemy's advance. Don't forget about your units' zones of control: if you place soldiers with an interval, you can make it impossible to enemies to pass, even having little army. But separating your units to much will put them at a disadvantage because of flanking bonuses.

Enemies can't pillage this citadel, even if they enter it. They will then die.

Despite randomness of map, you still have to place your two cities in certain positions to achieve maximum pressure on your future foes. And yes, you will have to wage war on everyone.
Your southern settler must go 1 tile south-west and settle there, right next to borders of Britain. Lead all your soldiers there and place them around your city, but more to the north-eastern side. Order your southern worker to build roads on tiles directly to the west and to the east from the city, and lead your other settler and worker straight west.
Your second city must be placed exactly at six tiles north-west and one north-east from Pretoria. This way of building your cities has one special advantage: it will put four of your enemy's cities in range of your cannons.

Swakopmund and Sa Da Bandeira have been added from the future with paint, but their positions are correct.

This positioning of Bloemfontein will also allow you to promise Zulus to not settle near them, without lying to them, because that place is out of Zulus' zone of interest.
Make one of citizens in each of your cities to work in workshop as early as possible, to get access to Great Engineers. You will later need them to boost production in your capitol.

Build cannons in both Pretoria and Bloemfontein. It will take about 17 turns each, and you will have to hold on until then.
Buy several tiles to the south-east of Pretoria, to prevent Britain from claiming them.
Make as many roads as you can in territory around Bloemfontein and Pretoria, even if you think, that you won't ever need them there. You can never be sure, when and where you will need to move your units, and high mobility can usually save you several turns of needless moving and even recapturing cities.
When you first meet Britain queen, exchange embassies with her, and then declare war. If everything goes well, their capitol defenses will try to ram your city, and you will finish them off with relative ease. Remember, that your foreign volunteer unit have special abilities: it has 50% defense bonus and it heals 25hp, whenever it finishes off its enemy. Always keep that in mind and use them wisely.
When you meet Germany and Portugal, declare war on them as well. Portugal will be your main source of VP until the end of the game, so get ready for infinite assault on Bloemfontein.
Order both workers to quickly connect your cities with each other, for easier cannon transfer. Then continue to build roads on every tile adjacent to your cities, to allow replacement of wounded units.
Your main goal in war with Britain is not only to capture both Port Elizabeth and Cape Town, but also to prevent britains from finding any new cities around you, or else you will get overwhelmed by enemies advancing from all sides. To prevent that, you should position your soldiers in a wall-like formation, and get ready to capture every settler you can. You them must order those workers to build farms and roads everywhere, where possible, to both boost your culture output and growth rate in your cities.
Germans will usually try to stick to their city Swakopmund, and will only try to attack, when provoked, so they won't be much threat, but will occasionally grant you some culture for carelessly placed soldiers. Another story is with Portugal: after first two riflemen killed by your city, lead one of your foreign volunteers there and fortify him next to the city.
When gaining policies, you should start with military branch to get bonus Great General, and then increase fighting capabilities of your units.

Red lines - importantplaces for roads, blue star - for citadel.
Placing roads like this will allow your volunteers to get to the enemy city in one turn from safe place.

Place your Great General on source of horses near Cape Town and build citadel there. This place is chosen for several reasons: you put more pressure and vision on enemy capitol, you get horses, you don't need to choose, whether to repair citadel or pasture, you might damage english and german caravans, that course between Swakopmund and Cape Town, and you will take away large amount of production in coal mine from Cape Town. Most likely you will have to abandon that place and keep your volunteers away from coast, to prevent bombardment by ships of the line, but now it will be much easier to return to this city later. Now you can focus on capturing Port Elizabeth. Bring second cannon from Bloemfontein and finish the job. Keep building cannons in Pretoria, while also building caravans in Bloemfontein. You will need exactly two of them, to bring production from one city to another and vice versa. After caravans are completed, start training foreign volunteers in Bloemfontein, until their amount will be sufficient to make defense of the city unbreakable.

With help of three cannons capture of Cape Town will go pretty smooth, and you will be able to turn on Portugal. If Zulus were attacked by both Britain and Portugal, they would likely be destroyed by then. If they were captured by Portugal, it's good and you can make peace with Victoria without delay, to get your cannons to work. If not, then you will be in more difficult situation, because you will have to greatly separate your artillery force and make one of your cannons advance on Ulundi and others - do defend Cape Town, Port Elizabeth and Bloemfontein.
When you get your second Great General, put citadel somewhere near Bloemfontein, on the tile, that is already occupied by your volunteer, to further fortify that place. Always remember to lead roads inside citadels, to further increase their defensive capabilities, by giving your units easier way to get in citadels in time. If you can allow your first citadel near Cape Town to be pillaged, those near Bloemfontein must be placed with much greater care, to make them as useful as possible. When placed right, citadel can allow foreign volunteer to stay fortified on one tile for fifty turns, while being constantly bombarded by four cannons and attacked from three directions by enemy riflemen.
When you get Great Engineer, bring him to Pretoria and let him build Ironworks for instant production boost. Your second Great Engineer, will either build factory or Heroic Epic, whichever you think to be most useful at the moment of his appearance.
In General, first two thirds of the game you will be building cannons and training cavalry in Pretoria, while also training foreign volunteers in Bloemfontein. Your workers must build roads on every tile, that might lay on the way of your units. Someone (most likely Portugal) will eventually find city right to the north from Pretoria. You should capture it fast, unless you want them to launch full assault of your capitol. Then you can focus on northern front, because Portugals will most likely ignore your other cities, if they won't see any units near their borders.

1. first citadel near Bloemfontein;
2. anti-Swakopmund citadel.

Proceed with attacking Sa Da Bandeira, to the north-west from Bloemfontein, and Swakopmund - to the south-west. Placing citadel in the middle between Swakopmund and Bloemfontein will make capture of german city an easy task, but you can do it only after defense of your own city is certain. When deed is done, make peace with Germany, or else they will put a great pressure on Cape Town with their Brandenburg Class ships. That is the reason, why you always need to build more cannons and cavalry units in Pretoria.

Sadly at some point of time your empire will become very unhappy. To at least somehow counter it, you will have to find the right moment for building circuses and zoos in your two cities. Also always keep track of all luxury resources in reach, and improve them as soon as possible. You can also trade with those of europeans, who don't hate you yet.
At around turn 60 you will have to stop amassing military might, and start building culture buildings in all your cities, starting with Writers', Artists' and Musicians' Guilds in Pretoria. Population there will soon be large enough to place two citizens in each of guilds, speeding up production of great people.
When you will get chance to choose any great person, choose Great General and send him north. All your great culture-based people should create their respective great works, to increase culture output. The only exception is Great Writer born near the end of the game: if he can write political treatise with bonus culture greater that amount, that his great work will give in the following turns, choose treatise.
At some point several european nations might declare war on you. Considering that none of them have land borders with you, they will all advance from the sea. That's why you need to build a large amount of cannons and cavalry units. You need at least two cannon shots to damage any city with 1 citizen for half of it's hp, which means, that you need at least two fresh cannons to recapture any city, that was captured from the sea. Of course, you also need cavalry to put that city under your control: after it is captured, you must lead cavalry out in the fields and repeat the process, until enemy is out of melee ships.
Important: you must prevent liberation of city by their original owner at all cost, or it might bombard your cavalry. 1 hp cavalry will surely die. The same thing is about letting any enemy to control city for more turns, than there are citizens: once civil resistance is over, city will bombard any of your units in it's range.
Bright side in all this is, that you will get even more bonus culture for all that sunken ships. Around that time you will have at least two properly leveled up cannons, and one of them might set up between Cape Town and Port Elizabeth, while other - between Swakopmund and Sa Da Bandeira.
At total you should have around 7 foreign volunteers, 7 cavalry units and 9 cannons. Even Portugal won't be able to keep constant pressure on such a force forever, and around turn 80 their army will finally start to leave your territory. This is your moment to strike, by leading most promoted cannons closer to borders, bombard enemy cities and capture them as specified above. You can use either worker or cavalry to make one step towards city, if it is out of vision range, then bombard it by all available cannons, and then lead your scouting unit back to prevent damage from city.

Some intel on positioning of original Portugal cities on western and eastern coasts.

Once keeping some of your cannons near Bloemfontein will start to be ineffective, you can lead some of them to the middle part of northern borders, or to the east: there are plenty of Portugal cities to capture. Always escort your cannons with workers and cavalry, to both protect them and build roads to increase mobility near the front. Portugal might always make a sudden assault on your middle city (their former city), and you must be ready to lead there some of your volunteers or cavalry for quick response. It will all require a large and expensive road network.
Most of your cities might get captured and recaptured over and over again, but as long as you keep Pretoria and Bloemfontein well-defended, you have nothing to worry about. Around 90th turn you will be first in VP even after capture of some of your cities, and you will further increase your lead to the 100th turn.

In this game you should've had built culture buildings and farms to win cultural race with Ethiopia, but in the end it turned out, that you can win only by proving your worth in this harsh world of evil colonial empires by bravely defeating their wicked warriors with your peaceful boer tractor. And that's all I have to say about that.

Sincerely,
realGuybrush.