I decided to play Germany after Spain and England.
It was a lot harder than those two, as conquering large amounts of Europe really hurted stability. Having enormous GNP, hammer and espionage output was fun though
Settings: Monarch, Normal, 600 AD. Score: 4269
( Are there any plans to boost the score for UHVs?)
I settled Wien, Frankfurt, Konigsberg (Great commerce spot. Made 600 beakers a turn in the twentieth century. It's one east of the river which leads to the Östsea in Northern Poland.) and Schlüsselburg (two south of Sankt Petersbourg). The latter one probably earned me the two war declarations of Russia, but the Russians are a backwards non-factor anyway before communism.
UHV goals : 1. Conquer Rom, Greece and France by 1870 AD.
The problem with the first city is that France likes Rome very much. For capturing, that is. They, however, did not bring enough siege and suicided their stack against Rome's defenders right after I finished bombarding down the defences, ensuring me an easy win with no losses.
The second problem is the nicely backstabbing Europeans. In my game, Russia decided to attack me. Their armies were pathetic, however, and a Woody 3 Landsknecht mercenary dealt with them. Then, just after I made peace with Russia, France decided to attack me and steal Rome with Knights before I could set up an adequate defence.
My army was, of course, on the border of Russia. I, however, was already plotting against them and preparing my stack, and I got Cuirs a few turns later. I easily captured France.
Then Spain decided to attack me.
With C3 Conquis and CR3 cannons, they sweeped my Cuirs away. I, however, reached Rifling in time to teach them a lesson and took back 'Burdeos' - Weird name. I like Bordeaux better - and Marseille.
Occupying France will hit your stability. You should of course have switched to occupation before conquering it, otherwise it will completely destabilize you. Build courthouses and wage no wars.
There will be a Greek respawn in about 1850 AD. They spawn with about 6 riflemen, which should be no match for your troops. I had Assembly Line and thus Infantries by then, but even plain old rifles and cannons should do.
2. Conquer England, Russia and Scandinavia by 1940 AD.
It is enough to have three cities in those regions (the native civilization can even be alive). Russia should be a piece of cake because of this if you founded three cities there soon enough, and relatively easy if you didn't. Russia is fairly backwards technologically for much of the game, and their UU is not much of a problem if you use Cavalries/Panzers to take a few cities. A strong Turkey attacked and collapsed Russia in my game, making it easy to conquer some independents, but it should be doable even if the civ Russia is alive.
The Vikings will usually have collapsed a few centuries before. More troublesome is preventing their respawns as Sweden. You can, of course, still kill them after respawn, but do so as soon as possible, before they can train any extra units.
England might be the most problematic of the three. After conquering France, tech economic and Industrial technologies. Being the first to Combustion means you can cripple England (and Spain, if you wish to knock them down a notch) by blockading with destroyers. Use Panzers (which are surprisingly enough better than Marines for Amphibious assaults) on transports and fighters/bombers to take out the English SoD, then take all their cities in quick succession. Do so as close to 1940 as possible, to minimize the chance of a respawn.
3. Be the first to complete the tech tree.
By building research, you should be able to finish the tech tree before 2020 AD (I did so in 1963 AD), so the only problem remaining is the AIs outteching you. England, the Netherlands and Japan usually are good techers. England you should have taken out, the Netherlands are fairly easy to conquer, with only one continental city, but Japan is more troublesome. Still, by beelining Computers - both for computer industry and the Internet - you should be able to win the tech race. Otherwise, you could use dubious tactics such as founding useless cities near Japanese territory, and then 'liberating' them, to slow their tech rate.
Tech path : beeline Liberalism, as you can win that race with ease by bulbing with great scientists. Then go for Printing press and it's 500 gold + 20 gold shrine. After that, go MT, Nationalism and rifling, for Occupation and Cavalries. Assembly Line and Industrialism (for your UP) are priorities, and Computers is useful too for technology.
Civics: Representation will really help in food-plenty Europe. I was running about 150 specialists near the end of the game, to give you an idea. Free market and SP are both viable options, but I've heard that SP gives stability boosts for large empires. The other civics you can choose to suit your play-style, but it is possible you will run into happiness problems early on, so maybe you could adopt one to counter that.
Post-game screenshots:
Never had this much research in one city (excluding OCC) before
Federal Republic of Germany right before victory.