World conquest (WC) is a goal you can set yourself when playing solo EU2. World conquest is achieved when you've eliminated all other countries in your game. World conquest can be made harder by attempting it with countries in worse techgroups: achieving it with a country in the "exotic" techgroup is a difficult feat indeed.
Strategy for World Conquest
Generally, there are two ways people go about WC. One is so-called "early" world conquest, typically starting in the 1500s when you hit land technology 14 or even as early as 9. The other strategy, occasionally called "late" WC, where the key tech is land tech 41, where you get conscription centers. A large European country building out a full set of conscription centers will go from supporting perhaps 500000 troops to over a million.
Other Hard Games
There are other hard games you may want to try to achieve. Some ideas:
- World Colorization: world conquest, but in addition you've got at least a trading post in every province. ("Colorization": in the political map mode, the entire world is your color.)
- World Colonization: world conquest, but in addition there is at least a colony in every province.
- World Civilization: world conquest, but in addition there is at least a colonial city (1000+ population) in every province.
- World Civilization++: world conquest, but in addition there is a full city (5000+ population) in every province. (I doubt this is even possible... but maybe...)
- World Conversion: you've managed to convert every province to your state religion. (This is possible... just barely.)
- Religicide: you've eliminated one or more chosen religions from the game. Interesting games here are to play a Shi'ite country and try to eliminate Sunni Islam, to play a Christian country and try to eliminate all other forms of Christianity, or to play a "crusader" game where you are a Christian country and try to eliminate Islam.