While my Buddhists couldn't into space, forcing them to settle for world conquest, they proved beyond any doubt that Theravada is the strongest religion in the game and Buddhism in general is great. Get your achievements while you can, as the Abrahamic faiths aren't worthy of being compared to it. Or something.
One-tagging is quite easy now, as long as you're willing to plan ahead a bit and suffer through the onerous micro, especially later in the game. I was lucky with my rulers (above average admin and average dip over time, and only one short regency council), but considering how much time there was left poor monarchs would've simply delayed it--multiple regency councils are a different story, but then that's the main reason monarchies blow. You'll see that I finished the game as a republic (republic dictatorship in fact), but I turned republic due to an event early in the 18th century, and at that point it didn't matter that much anymore.
I do not recommend trying this, mainly because Buddhism blows, but quite frankly any non-Abrahamic religion is a poor pick for one-tagging. While this is easier to work around in 1.13, 3 missionaries are still too few to effectively convert by yourself. Going through the solid Islamic block in central Asia and the Middle East is painful, and I was never able to completely eradicate rebels (raising autonomy in worthless provinces and converting the rest took care of the worst problems, and the huge FL and manpower reserves meant that no rebellion was ever dangerous, but it's rather tedious).
The world might've been unified under one banner, but the same can't be said for religion. At least Asia and the Americas look somewhat respectable.
Say what you want about the AI, but it certainly knows how to dogpile. I almost felt sorry for ol' Vijayanagar.
Everyone loves regency councils. Still, only a 2 year regency in almost 300 years (Ceylon became a republic through an event around 1720).
The sign that an Asian tag is moving up in the world: the day when Ming rivals you.
En route to Europe. Next stop: Ottomans.
Colony sniping? Exploration? Black Sea? This is how you westernize in style
I had originally intended to use Genoa, but as they managed to fall behind in tech I went with the backup plan--you want Rome for the extra missionary anyway, so why not use it to westernize?
About 100 years into the game. Ceylon has established a foothold in Europe as well as Africa and different parts of Asia.
Expansion around 1600.
The Buddhists strike back! I handled most of the conversions and U-Tsang took care of the northern parts.
The perks of tanking dip tech.
Whoever said that the quality of your generals and troops win wars was right on the money--quantity, after all, is a quality of its own.
If only these events could happen earlier and more often. Republics are great, but at this point in the game it didn't matter much.
