This is going to be a list of every country in the game, and the reason to play as them (I hope). Obviously, I've only played games as about 10 different nations, so it'd be pointless for me to make this up on my own. So without further ado, I'm going to ask the Paradox community to suggest countries and (very short and sweet) reasons for playing them.
Aachen - First in any dictionary, Aachen also makes an excellent first-time OPM, with superb trading potential and no immediate threats from neighbors. Soar in tech and accumulate a massive treasury while waiting for the right time to expand.
Achaea - Challenging crusader state with poor sliders and position. You are very weak, but protected by western powers via guarantees and spheres of influence. With nearby nations to invade, you do stand some chance.
Albania - (Must be realeased from Ottomans first, or 1444 start) A poor Balkan OPM that the Ottomans have a core on; luck and abuse of your genius starting leader is vital to survival. Even if you can outlast the Ottomans, any number of local blobs are available to take their place, but there is breathing room which can provide a good base for Albanian revenge.
Alsace - an OPM near France and Burgundy, but not immediately bordering them. Alsace starts as a theocracy, and has good potential for a peaceful trading nation or some expansion.
Anhalt - a one-province German minor, located near larger minors such as Saxony and Thuringia. If some nearby provinces can be seized, Anhalt can expand more easily without alliance-chains bogging them down.
Ansbach - A good first go at playing a German OPM. None of your immediate neighbours are very big, but they all have an interest in you from the start.
Aquileia - Middle-sized north Italian bishopric. With two gold provinces, and Venice's cores on your land, it can be difficult to survive amon jealous neighbours.
Aragon - trapped between Castille and France, this is one of the more challenging powers to play. Annexing Navarre and forming Spain is one route of expansion; forming a powerbase across the Mediterranean in Italy can assist to that end.
Athens - once a powerful Greek city-state, Athens is now dwarfed by its neighbours and Mediterranean rivals. Consolidating the Balkans, or the nearer coasts and islands, is a must for forming a powerbase.
Austria - strong HRE power, can become emperor quickly and use its missions to dominate Italy and Germany. Austria is also a great nation to play as a diplomatic power. By utilising its strong position within the HRE and the extra diplo skill, you can expand all over with PUs. Its position on the outer edge of the HRE means it can expand outward at the same time, backing diplomacy with force.
Bar - incredibly small, challenging nation. It's almost impossible to survive the opening years.
Bavaria - medium sized HRE state between Austria, Bohemia, and France. Landlocked, and with poor sliders, this country can be very fun to play.
Bohemia - a non-German member of the HRE which has to contend with any number of local powers, but has the ability to dominate Europe.
Bourbonnais - An OPM vassal of France, this nation has great trading potential and is immediately able to join the HRE. When the chance arises, break free from France and invade the Low Countries - become the next Burgundy, and then the next France!
Brabant - a challenging country with poor sliders, Brabant has Burgundy as a neighbour which has a mission to conquer your provinces. Can form the Dutch Nation and has the national decision to gain Belgium's territory and become an empire.
Brandenburg - Become Europe's dominant power by forming Prussia. Contend with other likely candidates, your neighbours Bohemia and Poland.
Bremen - surrounded by provinces of the same culture, gets early a CB against Denmark, has a strong ally in the Hansa as well as a port. As an archbishopric, regency councils are not a problem.
Britain - a great position to colonise, and invincible position mean that Britain can have a powerful empire that fears no one.
Brittany - Average French nation which can easily take on France if you know what to do. Is also a good nation for trading, and in a position to colonise. If you so wish, you can choose to completely ignore Europe and simply conquer the New World, planting your awesome flag and attractive shade of lilac across the uncharted wastes.
Brunswick - Another one of Germany's many one-province minors, Brunswick is still capable of gaining size against its foes.
Bulgaria - If you ever get the chance to revolt from Ottoman Empire your next goal is to remain independent. If you succeed your next goal is to defend from Hungary/Austro-Hungary, Wallachia and Serbia, and become the only power in the Balkans.
Burgundy - great missions, and can take on France and end their reign of terror!
Byzantines - as above, but with the Ottomans. The Byzantines are much more challenging, however, as an Orthodox country that is already in decline.
Castille - has to contend with its neighbours of Aragon and Portugal, before expanding north to face off with France, or pushing the Reconquísta back into Africa. Once it has consolidated Iberia it can begin colonising the New World.
Connaught - westernmost and poorest of the Irish minors. It borders the other four Irish provinces, but this leaves it vulnerable to attack. Is able to unify Ireland, but only once Meath is retaken.
Corfu - remove the shackles of Venetian domination, and then conquer Greece and south-east Europe.
Corsica - (must be released from Genoa first.) Invade the smaller Mediterranean states and slowly spread your coastal empire.
Croatia - a struggle to survive as Austria, Hungary and Venice see you as their playground. The Ottoman Empire, of course, is another huge threat.
Cyprus - island country, in a position to retake the Holy Land in the name of Christendom.
Denmark - unite Scandinavia's poor provinces and dominate northern Europe. You are in a position to prey on the northern German minors; but only if you can evade Sweden's armies. Denmark is capable of establishing itself as a powerful nation, but cannot risk open war with Sweden early on.
England - A powerful island base to invade Ireland, Scotland and the Continent. Security is guaranteed by the English Channel, and you are in a perfect position to colonise the New World.
Epirus - Naples, Byzantium and the Ottomans have cores on your single province, and tend to declare war within the first days. Epirus tends to be seen as a rather hopeless minor.
Finland - (must be released from Sweden first.) Beat Sweden, Norway, and Denmark, form Scandinavia, and own the Baltic Sea. Russia and Sweden will always be serious threats, however.
Flanders - (must to be released from whoever holds the territory). Form Netherlands by conquering northwards and resisting the encroachment of both France and the HRE.
France - one of the most powerful countries in the world; once it has unified France and defeated its rivals in Britain and Spain. Then, it can become a massive colonial power.
Friesland - starts off very small, but is able to form the Netherlands, take over France and eventually conquer the world! As with most nations in this region, Friesland is a member of the HRE, and therefore boxed in, to both its benefit and its disadvantage.
Genoa - wealthy merchant republic that can defeat Milan and consolidate Italy, or use their Black Sea provinces to invade Russia itself.
Georgia - small nation that must rely heavily on minting and loans if it is to withstand its enormous neighbours.
Germany - central European power with great potential to expand into Italy and France.
Granada - Europe's only Muslim nation. The last remnant of the taifas, standing up to the Christians is nearly impossible.
Gotland - OPM island off the Swedish coast. Must resist assault by the Danes, Swedes, Teutons, Russians, and Poles; and anyone else nearby.
Guyenne - Must be released from France, but it can be about 1/3rd the size of modern France when released with all of its provinces! There's nothing quite like painting France a paler shade of blue.
Hesse - Nice, central 3-province state in the HRE surrounded by many weakling OPMs to play out against each other and finally gobble up if you're good at that. Good Emperor potential, while not too easy like Mecklenburg or Austria. Additionally, they've got one of the nicest flags you could ask for and a very decent national color.
Holland - The best moneymakers in the world; no one can beat you at trade. Holland is in a good position to form the Netherlands and start building a colonial empire.
Holstein - The little country that could. Denmark, perhaps with a little help, is very likely to overextend themselves, and that is when you strike. After that, you're a German minor, outside the HRE, but neighbouring several small members, with numerous routes for expansion.
Hungary - A medium-sized power in the Balkans, with fair tax values but poor manpower for its size. Hungary has the own-cultured vassal Transylvania. Its biggest problems are Austria with her missions and the giant Ottomans to the south, but an alliance with Poland and/or Austria early on can be both a deterrent and an opportunity into Italy. The Imperial Crown is also a possibility for Hungary.
Ireland - attempt to take Britain in revenge; or cross the Atlantic for a colonial empire.
Kurland - An independent nation on the Baltic Coast. Try and establish a power base in your area and then move to America before a local power such as Sweden annihilates you.
Leinster - the eastern side of Ireland borders England's foothold on the island. In order to unite Ireland it needs to drive the English out of Meath.
Lithuania - incredibly powerful Baltic state, but limited by its junior status in a union with Poland.
Lorraine - Lorraine is in a great position to go conquering in either France and Germany, but first must withstand the might of Burgundy or France; or both.
Luxembourg - The only European OPM in the game to survive until modern times, and doing just that would be a challenge in of itself. It's also one of very few French-culture HRE states; if you can survive and expand, you may recreate Charlemagne's empire, uniting the crowns of the HRE and France.
Mantua - An OPM in the north Italian heartlands, with more powerful neighbours including Milan and Venice. For early expansion Zeta and Ragusa make good targets, and a defense against annexation. Mantua is a small, but rewarding country - success will not come easily to you.
Mazovia - Surrounded by three large states. Poland has a mission to vassalize you, and the fact that you are landlocked doesn't make things better.
Meissen - an interesting German OPM, with a Saxon culture it can go on to form Prussia. It is possibly one of the more difficult ways to do so; hence the challenge it provides.
Milan - Milan has what is easily the best chance at uniting Italy behind its dynasty. With a lot of wealthy, heavily-populated provinces and HRE membership, it's relatively safe from attack, but will have to time its battles well, because the Emperor and the Pope both have a stake in preventing Milan from taking the Iron Crown of the Lombards.
Moldavia - Bordering the Golden Horde, the recipient of many a Jihad or Polish army, but if you can survive and extend your borders you can form Romania and dominate the Balkans.
Montenegro - A weak Orthodox OPM feudal kingdom on the coast of the Adriatic flanked by two regional powers and several weaker states. The only real expansion options are Ragusa or overseas unless you are lucky and a local giant collapses. Be warned: you are one of the first Balkan States to be eaten by the OE in most games.
Morea - (1453 start) Restore the Byzantine Empire as Constantine XI's idiot brothers, overcoming terrible sliders, the invincible Ottoman Empire, and the sticky fingers of the Venetians. From there the Balkans and Eastern Mediterranean lie open.
Muscowy - wield the might of Russia against the Golden Horde. Good missions, but poor, vast provinces. Muscowy is also a very backwards country in terms of technology, and susceptible to attacks from its powerful, expansionist neighbours.
Munster - southern most of the Irish kingdoms, has the River Shannon to defend itself from its rivals. It can unify Ireland, but only once England has been forced to relinquish Meath.
Naples - Italy is fragmented, and you have a nation large enough to take advantage of it. Sicily is your only nearby threat. The western Balkan coast is also a good target for Naples. For an early powerbase, moving northwards into the highly advanced, but small states can give the necessary technological boosts.
Navarre - wedged between every single one of the Western European powers, but has the sliders to become incredibly wealthy if it survives their onslaught. A likely target of Aragonese vassalisation, but this can be used as a chance to colonise and await your release. Be wary of overextension, however.
Naxos - Escape from Venice and the insular powers, take over Greece and use it as a base to destroy the Ottoman Empire
Netherlands - Challenging neighbours, strong provinces, very fun medium-empire game. An almost-guaranteed to be successful trading nation.
Northumberland - (must be released from England first.) Lodged between Scotland and England, Northumberland has to defend itself from much more powerful enemies if it is to succeed, but it can be very rewarding if it survives.
Normandy - (must be released from France first.) A historically significant nation, with a position in northern France, trapped between England and France, Normandy requires a lot of political work just to survive.
Norway - Challenging neighbours, but has the bases to begin colonizing North America early in the game. Also protected by a Personal Union if you want to play peacefully.
Novgorod - make your Merchant Republic big and rich, or take over Asia by forming Russia. One of the most powerful Russian states, but, as with the rest, technologically behind. Its missions can be hazardous, however, as Lithuania and the Teutons are massive threats.
Palatinate, The - One of the HRE's middle-sized states; The Palatinate starts with 3 provinces, and is full capable of expanding to become the lead power in Germany. Often a favourite for the Imperial throne, this is one minor that is not to be taken lightly.
Papal States - theocracy, easily able to control the curia. Able to form the Kingdom of God - what could possibly be more fun?
Poland - fragmented western neighbours, and the advantage of wielding Lithuania's power as well as your own.
Pommerania -a tough HRE state, lodged among the Teutons, Poland and Brandenburg, but you have a good chance if you can manage to snatch neighbouring Danzig. Conquer the Baltic and north German states to build a power base in Europe.
Portugal - Unlikely that you will ever be in a large war, and in a good position to start its colonial empire. Spain, however, will always be a serious menace.
Provence - A long-suffering French minor; Provence's initial position in an union under Naples is a dual-edged sword - it tends to make the French look away, but it severely limits your options. You never know when you'll break free, so you must be prepared and totally ruthless when the opportunity comes.
Pskov - A Russian landlocked one-province minor trapped between Novgorod and the Teutonic Order. You have trading sliders which make a good economy possible, but only if you can withstand the might of two local giants.
Ragusa - A weak Catholic OPM flanked by two regional powers and several weaker states. The only real expansion options are Montenegro or overseas unless you are lucky and a local giant collapses. Ragusa is most likely to be eaten by Hungary early on, but is occasionally taken by the Ottomans.
Riga - The only Latvian nation in the 1399 start, wedged in the Teutonic Order's territory, and saddled with mediocre sliders and poor technological position. Regardless, often in a position to take advantage of the Teutonic Order's occasional collapse.
Ryazan - Trapped between Muscovy and the Golden Horde, they have no real advantages. Muscovy has a mission to anex you and the Golden Horde is more than happy to declare war on a heathen. Another of those hopeless Russians.
Sardinia - defend your island from the Aragonese, and attack the weak North African countries. Early expansion is key to guaranteeing your survival.
Savoy - a small nation lodged between the Italian states and France. Historically, it formed Italy, but in game stands little chance against its many enemies.
Scotland - because Delra failed 12 times (yes, 12!) playing them in HttT and if you can pull it off yourself it will make you feel better.
Serbia - an Ottoman vassal, wedged between Turks and Hungarians. Though a middle-sized power, Serbia's position and Eastern tech group make victory a challenge. However, nations such as the Byzantines are in similar straits and may be willing to lift Serbia's shackles.
Sicily - an island nation with two giants to worry about, Naples and Aragon. There are, however colonisation options in north Africa even for this small country. It is not powerful enough to contend with large nations, but stronger than many Mediterranean minors.
Siena - a coastal OPM in central Italy, Siena has chances to expand into neighbouring minors, until it runs into larger foes such as Milan.
Silesia - Not in the HRE, with the only potential targets far away in Russia, surrounded by powerful neighbors that could destroy you, and bad sliders; the eastern-most European country in the game is nearly impossible. Add on to that the fact that you're a Bohemian vassal...
Styria - two gold provinces, with a CoT nearby to conquer. Austria and Hungary are nearby to watch you; with luck they are not greedily eying your lands.
Sweden - The most powerful Scandinavian nation, but often at war with its jealous neighbours.
Switzerland - Landlocked HRE nation with very good sliders, provinces and a special government which makes it easy for you to become wealthy. Borders France and the Holy Roman Empire states.
Teutonic Order - weak starting provinces, but a strong military orientation and good, central position means you can dominate in any of many directions. Regency Councils are not a concern.
The Hansa - Starts with a CoT, is rich with sea access, and has good missions to conquer Denmark and other nations. It can also form Germany.
The Knights - last remnant of a once-powerful Crusading order, but still have the possibility of resurging by invading the weaker Mediterranean countries.
Transylvania - its starting position is fraught with danger once you break the vassalisation with Hungary, and is very poor at the start. Nonetheless, many of its neighbours lie open for Transylvania to conquer.
Trebizond - A small one province minor on the Black Sea, with powerful enemies and few allies. One of the last remnants of the Roman Empire, Trebizond is a real challenge, even for the experienced.
Tuscany - Landlocked OPM at the start, but with great potential to be a trading powerhouse and form Italy. In earlier versions, Tuscany was a significantly large power.
Ulm - because Ulm.
Ulster - the northern Irish kingdom. It has borders with England's foothold in Meath, as well as the vulnerable Connaught. Once Meath is reclaimed it can unify Ireland.
Venice - Very strong neighbors, possessions scattered all over Eastern Mediterranean means you're up in everybody's business. Extremely defensible home province also makes for epic hanging-by-a-thread struggles.
Wales - A small nation, nestling in the shadow of the English giant. Options are few - Brittany or the Irish minors are potential allies, and, if possible, England can be forced to release Cornwall.
Wallachia - minor nation lodged between Hungary and the Ottoman Empire.
Yaroslavl - One of the weakest candidates for forming Russia. A real challenge to play as, but not impossible.
Zaporozhie - A rightfully forgotten country in Ukraine with an embarrassingly angelic coat of arms for a Muslim horde nation, which it usually ends up to be.
Asia and the Middle-East
Ak Koyunlu - (Appears in 1402, Timurid vassal until 1404) Surrounded by the Ottomans, Mamluks, Timurids and Golden Horde, with a tribal government and awful sliders, this poor country at least has a nice national colour! With two Christian neighbours against which Holy War can be fought, (one with a gold province), and once the Timurids collapse your path to the east is free to form Persia or the Mughal Empire.
Armenia - (Must be released from the Timurids first.) Surrounded by power hungry Muslim neighbours and you only have 1 province of your own culture! Expansion is almost impossible.
Astrakhan - At a later start date Astrakhan has plenty of weak neighbors and plenty of nearby hordes for colonization. Your greatest rivals and foes are Kazan, Lithuania, and the Ottomans. Crimea is a target for westwards expansion. Reform your government and westernise in a bid to dominate the world (or at least get another province). They also have an awesome Flag and Colour.
Ayutthaya - spread Buddhism throughout South-East Asia and oppose Ming from the relative safety of the southern edge of the continent.
Bihar - home of Asia's 2nd most valuable CoT, but a likely target of Delhi's expansion - backed by cores on Bihar's land. Though Technological advancement is easy, military does not come as easily to Bihar.
Chagatai - good sliders, and is a much more challenging way to form the Mughal Empire due to its smaller size.
Champa - Champa starts out Hindu in south-east Asia, surrounded by Buddhist and Confucianist countries. Holy War is a distinct possibility.
Dai Viet - Ming has mission to annihilate Dai Viet, leading to huge challenges for this Asian country. However, if Ming overreaches itself and collapses whole new aisles of opportunity will arise.
Deccan - A fun, challenging Indian medium power squeezed between Delhi and Vijayanagar. Their position in the centre of India, plus the Holy War CB, lets them easily annex all of the nearby minors, and even Vijayanagar.
Delhi - Delhi has possibly the best province in the world, is a Muslim nation, yet all its provinces are Hindu, and is surrounded by Hindu states. You have claims on Bihar, one of the walthier local CoTs. By conquering that province, Delhi can become an incredibly rich mercantilist state.
Golden Horde - Fairly easy route to government reform, and then Europe is your oyster! Focusing on government tech and westernisation will make you fall behind in land tech, but what does that matter if your rivals have a third of your forces?
Jalayrids - moderately powerful Sunni nation lodged between huge Shi'ite ones. If it can consolidate it's position, however, it can be more than a match for its bigger neighbours.
Japan - An isolated, unified island, and last to meet the Europeans. Essentially an Asian Britain. But why play as England and fight France when you can fight Ming? In a perfect position to colonize Eastern Asia, and then move on to Eastern Africa. For an even greater challenge, the Pacific coast is within reach of colonies you may place in Hawaii or Alaska. In Divine Wind, Japan starts as a group of conflicting Daimyo-states to be unified, rather than as one Empire.
Karaman - Starts in an alliance with the Timurids against the Ottomans. Both its OPM neighbours are guaranteed by the Timurids, leaving expansion tricky. If successful, Karaman can keep expanding into the Timurid's vassals (assuming immense luck...) and be in a position to defend itself. Eventually, however, the Ottomans can be supplanted and replaced with a Karaman Empire.
Khorasan (not available in 1399) - A non-horde, Muslim-tech, Shi'ite, Persian country located right at the boundary between Persia and India. You can form the Mughals or Persia - but only one.
Kingdom of Jerusalem - A Catholic OPM surrounded by powerful (and angry) Muslims, the Kingdom of Jerusalem really is Heaven on Earth. It brings its own rewards for being such a complicated nation to form and to play as.
Korea - You're stuck between Manchu, Ming, and Japan, but if you can conquer Manchu you have a prime position for expanding both into Mongol territory and Indonesia. Try to build a mighty colonial empire and eventually take on Japan.
Malacca - if you can avoid an early grave, Malacca's CoT and rich provinces make for a very wealthy nation indeed. Inheriting or vanquishing your neighbours can lead to dominance in the Indian Ocean; a route which can be bolstered with or replaced by colonisation of the remaining islands.
Manchu - Manchu's location directly above Ming may be dangerous, but victory is possible. Replicate history and take over Ming China to become the dominant power in Asia.
Manipur - an extremely challenging Asian OPM , lodged between bigger neighbours. Fortunately, none of these, bar Muslim Bengal get an instant CB on you, but you are in no position to expand, are very poor and not really able to field any army. It is only a matter of time before your bigger neighbours start pushing you and go for your only province, unless you can find a weak target nearby.
Ming - one of the most powerful countries in the game. Need more be said? Simple to dominate Asia, and from there, the world
Mongol Khanate - a vassal of Ming, so there is no risk of outside attack, but almost no hope for freedom from your overlord. You are in Altaic culture union so everything from your home to Azerbaijan to Ukraine can be yours with no culture penalty.
Oirat Horde - a poor, tribal nation in bad tech group, but attrition can work in its favour. Let foreign invaders die in your desert and then spread war among the east-Asian empires as you expand into them, then westernise and reform the government, and the continent lies open to you.
Oman - a potential trading giant of the Middle East. Great challenge fighting Timurids and Mamluks in the desert, once you've defeated your neighbours.
Orissa - The real challenge of the subcontinent. Ringed by ambitious enemies, but without advantages such as Rajputna's size, Bihar's CoT, or Vijayaganar's location. Even relatively good sliders might not ensure victory, but they will help.
Ottoman Empire - a strong power that threatens Christendom, itself lodged between a collapsing Roman Empire and the mighty empires of the east. It often has to fight wars on many fronts. The advantage of the Holy War CB means that it's easy to invade Europe with almost no infamy accrued.
Persia - immensely powerful Shi'ite empire. Easily capable of becoming a world-spanning empire as it wipes out the Ottomans and Europe to the West, or other Muslim states around the Middle East.
Qara Koyunlu - Weak starting position, no fortified provinces, a tribal government, and sandwiched between two of the foremost powers in western Asia, the Golden Horde and the Timurids. However, you also have the choice of forming two different nations, Persia or the Mughals, as well as multiple opportunities to utilize the Holy War casus belli.
Rajputana - a large, local power with mediocre provinces sandwiched between Delhi and the Timurids. Either have the capability to destroy you, but if you survive and westernise there are few limits to your ability to expand.
Saruhan - a tribal OPM, whose Ottoman and Byzantine neighbours both have cores on its land. Survival will be difficult, but at least you have the best flag in the game! Go forth in the name of Isengard!
Sharjah - small, strongly Sunni state, situated so slaughtering some Saudi's shouldn't seem so silly.
Timurids - Very shaky starting position, despite being a powerful country. Though quite capable of annihilating its enemies, its tribal government leads to frequent rebellions, but can form the Mughal empire by conquering Delhi.
Vijayaganar - powerful Indian empire; very different to the players used to European nations.
Yemen - though the threat of Ottoman, Persian, or another power's invasion is always there, Yemen does have the advantage of being near extremely weak but large African Nations that provide cheap and easy conquest, and a powerbase for later growth.
Adal - A mid-sized sub-Saharan nation, it is in a terrible tech group but a useful religion and government type. Very careful management of borders and relations is essential until you can grow, and westernize. A fun challenge.
Algiers - bordering Tunisia and Morocco, Algiers is a common target of the Spanish kingdoms. If you can consolidate the Mediterranean coast under the one Sultan, you may stand a fighting chance.
Ashanti - central African OPM with tribal government. Fend off Mali and your neighbours to conquer Africa, but watch out for the colonials.
Ethiopia - surrounded by enemies, Ethiopia is the one Orthodox nation in a sea of Islam, with most of its provinces not even the same religion. It can hold its own comfortably against its southern neighbours, but if the Mamluks, or any more northerly nation, move south, life can get a lot harder.
Funj - a Nubian nation that isn't seen by many players, because it is absent in 1399 start (appears in 1503), Funj starts out as Christian (though in 1530 it becomes Muslim in history files). Most things which are said about Ethiopia can also be applied here, though in Funj's case the larger shared border with Mamluks (and if you start at a slightly later date, Ottoman Empire) and poorer provinces pump the difficulty of your game up.
Kongo - a small nation, firmly lodged as far from European colonisers as possible. Once they arrive, however, there is nothing this technologically-behind country can do.
Mali - in a nice east African position, Mali is a bit removed from the Spanish onslaught. They'll come nevertheless and give you a chance to westernise, or die trying. It is one of the largest African nations.
Morocco - A North African power which must try to defend against the might of the Iberian nations. If successful, it can create a continent-spanning Muslim empire from its relatively wealthy base, with a gold province and excellent sliders for a trading nation.
The Mamluks - able to defeat any of its rivals, eventually consuming all of the Muslim nations. From then, Europe is its playpen.
Mutapa - east African tribe with one neighbour. Destroy Swahili and then go on to attack the Middle East from the south, if you can modernise your army.
Songhai - You're an African monarchy in the middle of a number of tribes. Take advantage of their internal problems to expand. You should be safe from the Europeans for a while, take that time to Westernise and you'll be in prime position to colonise South America or India.
Swahili - small nation that must rely heavily on minting and loans, but is inevitably doomed regardless.
Tripoli - 3 province country on the Mediterranean. Try to take out your rivals the Mamluks, Morocco, Algiers and Tunisia to become a local power. Westernisation is key: if you dont westernise, Crusading Christians will wipe you out.
Note: once the colonial powers arrive, anyone in the Americas is pretty much screwed.
Aztec Empire - start of very small, try to overpower your neighbours. Given the technological equality in the New World, this is not a hard feat.
Chimu - Only one neighbour; the much larger Incas. Once these have been vassalised, Chimu may eventually hold the entirety of South America. Remember to use your slider changes well, and prepare for westernisation.
Columbia - A colonial revolter with much more powerful neighbours such as La Plata, Spain and Mexico. Allying with some of the other revolting states may give you the help you need in driving out the foreign oppressors once and for all, however,
Creek - a nice position in the Americas, with two neighbors to wage war with, and a tribal government keep you busy for the first century before the Europeans. Once the colonisers arrive, it becomes a survival game.
Haiti - Caribbean colonial revolter state. Fight for dominance over the other American states, such as USA and Mexico, and drive out your resistance.
Huron - Conquer your neighbour and then prepare to resist the advances of Portugal (if you're lucky) or GB/Castille (if you're unlucky). Westernisation must be done as soon as the Europeans arrive if you are to survive their assaults.
Inca -*Only one neighbour; easily-bullied Chimu. Remember to use your slider changes well, and prepare for westernisation, or the colonists will annihilate you. Sound familiar?
Iroquois - see "Huron".
Mexico - boasts possibly the best flag in the Americas. Not only this, Mexico also owns large tracts of land in Spanish possession, but as they have their hands full with other revolting nations there is a chance of pulling through as one of the most powerful states in the Americas.
United States of America - Possibly the most long-winded nation name, America starts off in the late game with a good position and sliders. It has to fight off the colonial powers as they attempt to reconquer it. Very good, fast-paced game.
Indian and Pacific Oceans' Islands
Brunei - the Behemoth of South East Asia, no AI can take you down until you share borders with Ming. With your great capabilities, reaching Ming's frontier is only a matter of time.
Ceylon - with just two provinces you can't compare to the Indian powers, but oddly you are almost entirely forgotten. An excellent game for waiting, and it's all too easy to colonize when you get the chance. Of course you should westernize first..
Majapahit - a Hindu state in Java surrounded by Sunnis, often the victim of holy war. You can colonise the Spice Islands, Australia, and the Philippines.
Makassar - an OPM with friendly neighbors, except Majapahit Hindus, but when they attack you have possible aid from three Sunni powers will come to your aid. You can also easily colonize Eastern Indonesia, Australia, and the Pacific from your position.
Malaysia - Malaysia is a Muslim power in the middle of Asia. Has the sliders and the AMAZING CoT, both of which can turn you into a colonial and trading power, while you're in a race against time to become strong before the Europeans start colonising the Indian Ocean.
Maldives - reasonably out of the way, and with quite a nice colour. Forays into India or Southeast Asia may yield conquests for this otherwise hopeless archipelago.
Ryukyu - possibly the hardest nation in the game; a tiny, Pacific OPM, Ryukyu stands hardly any chance of survival. However, with some luck and good management you can create a small empire in South-East Asia, if you escape the ever-vigilant Chinese.
Sulu - a two province Philippines country. You are in a position to dominate South-east Asia from your island base.