Knights of Honor

Knights of Honor is a medieval strategy game for Microsoft Windows developed by Bulgarian Black Sea Studios. It was published by Sunflowers Interactive in Europe in 2004 and Paradox Entertainment in North America in 2005, and is available on Steam. In it you are in control of a kingdom, empire, duchy, emirate or several other kinds of states from that period. You build up cities, burn and loot enemy towns with your marshals, earn gold or goods with merchants, spy on other nations with spies, make and break alliances, fight crusades, slaughter rebels and destroy history!

There are three main religions of which the nations are part, and to which they can convert: Roman Catholics, Orthodox Christians and Muslims. There's also pagans, but you cant become pagan, and few nations start pagan. aside from some bonuses (Roman Catholics get a boost to income, Muslims can call for jihad which produces free, weak units that attack other religions' armies) and negative effects (Roman Catholics can be excommunicated by the pope, and all, but have to send armies to fight in crusades when they are powerful).

The AI tends to make stupid mistakes and rarely builds up more than a handful of armies, even when opposing nations are being invaded from all sides, so wars tend to consist of them raiding villages, and you taking their provinces. As the game goes on, they build great defenses, so siege weapons are a necessity.

There are four ways to win. The easiest (comparatively) is to get all "kingdom advantages" (basically improvements from having certain trading goods), which requires a large income and at least eight cities with harbors, as well as many different resources, which usually take a dozen or so different provinces.

The second is to be elected emperor of all Europe. You need to be at least the second most powerful nation to even be considered, and you need great relations with other nations for them to vote for you. The election happens periodically, and it's rare for any nation to even vote one way or another.

The third and hardest way is to conquer everything. Athens, Rome, London, Jerusalem, Paris, basically all of Europe, North Africa, and parts of the Middle East and Asia. Obviously this is the hardest, but the most rewarding.

The fourth way, similar to the second, is to "claim the title". Basically, you claim to be emperor of all Europe. If you are friendly enough with the major powers and have a good army, they might vote you in. If they don't, then most of Europe hates you and you end up with a rare case of the AIs doing serious damage. Generally, by the time this can work, either number two will have happened or number three is within reach.

A sequel, Knights of Honor II: Sovereign, is scheduled for release in 2020.