How do you have children in RTKXI?
You don't. It's very much a historical simulator in the sense that if you were meant to have children, you will; if you weren't, you won't. (I believe even if, say, you kill Cao Cao very early, if his faction survives, about 30 years later, his fifteen-year old youngest son might pop up. :shock: )
Pretty much all the games since 6 seem to have had a Windows version, according to MobyGames and the KOEI forums. XI is just the first to have come out for the PC in English since RotK 5.
At one point I was bored, so tried everything between the beloved ROTK 4 and the latest (11). 5 is notable for introducing tactical formations to battles, which had a big role to play historically. It's also very different in the sense that you don't really have the empire-city relationship anymore; instead of having each city as a separate entity where you move people around and so forth, your empire in most respects is treated as a single one.
6 adds nothing new and they tried to get into the whole Windows menu style with movable menus, but it's all Win95 grey UI and everything is pretty crap.
7 is excellent, and began the whole RPG-ish "Play a Character" thing. You could start off as / become a nobody without a sovereign, work under one (usually as a general or as a strategist), or a sovereign in your own right. You had things like annual duel competitions that you might try and win as a general to gain cred, or poetry competitions as strategists (both of which are historically accurate: there is a famous account of Cao Cao holding an archery contest for his generals, whoe nded up brawling on the ground over the silk robe at stake.) You also visit people and send them letters to build up relationships, which can hook you up with sovereigns, get you nifty bonuses or help you bribe them.
8 (or was it 9?) tried an Age of Empires-like battle screen with walls and buildilngs as opposed to your standard "Nature & You" ROTK terrain. Good idea, but graphics was horrible, interface/control was nonexistent, battles made no sense and... bluh.
11 is actually the best in the series in a long time, bringing it back to a relatively challenging and well-balanced strategy that you saw in the first four iterations. You could complain about the massive role individuals have to play in the battles, but that's accurate to the setting and also pretty accurate historically as well. For most of this period, armies were very ill-equipped, mostly being masses of levied peasantry without uniform equipment or a lot of training, and a single powerful warrior, fully armoured and on horseback, could realistically wreak havoc and kill hundreds and emerge unscathed - and equally, his defeat could mean a massive panic for thousands.
I doubt that it was ever released in English, but there were also three "RPG" type games from KOEI based on the Romance of the Three Kingdoms. They were... well, they were basically Final Fantasy Tactics. Some story, a town is a vehicle for you to buy crap and move on the story, then set piece fights. There was one that followed the story of Liu Bei, one that followed Zhuge Liang, then one that followed Cao Cao (in that order, chronologically). Each notable individual would have a pre-determined class (such as "Strategist (really, Mage)", Footman, Knight, Bandit (mountain movement), Supply Wagon (healer), Drummer (morale), Catapult, etc), and would level up progressively. The first one, especially, was actually damn hard; without grinding you'd have to always look for the quickest way to win or get out of the battle. They get pretty damn stupid when they become fictional in the end (since historically, none of those three succeeded in reunifying China) - Cao Cao faking his death then coming back, and stuff like that. But in a light-hearted way it's quite fun, and the combat is comparable to FF Tactics or the Shining Force series.
I remember the earlier ones I downloaded from Home of the Underdogs being much more fun.
RTK4 and 2 are the pinnacles of the series.