The expansion is fairly compatible with older save games; however, previously made ironman save games aren't compatible.
The DLC goal is to give some unique gameplay and flavour when playing as a nomadic ruler, different from the fixed settlements of Europe, while struggling to become the Great Khan – the Ruler of the Sky. This includes:
- Nomadic rule: contrary to tribal governments, nomads do not have permanent settlements. Nomad hordes simply have a total population, which grows relative to how many empty holding slots exist in their provinces (steppe provinces are best, but some other terrain types are also acceptable). A large fraction of the total population counts as Manpower, which is used to raise regiments (similar to retinues).
- Clan politics: with mostly empty holdings, nomads tend to have a lot fewer normal vassals than other realms. This is compensated by a variable number of member Clans, that fight for dominance. Mechanics include splitting/absorbing clans that get too large/small, and proclaiming feuds and blood oaths.
- Nomad succession: nomads no longer use ultimogeniture, but the most prestigious son or brother inherits. To get control over the heir, a nomad ruler can send his most promising brothers or sons to become mercenaries.
- Dynamic mercenaries: mercenary bands can now form dynamically, becoming available for hire by rulers in the general region. As they earn money, the size of their regiment increase.
- Raiding adventurers: should a horde lose its last province, the tribe will still exist, and may use its remaining armies to conquer another land in which to settle. Adventurers will use the money they gain from raiding to recruit more troops, and when they have grown to a certain level, they will try to become landed.
- Silk road: rulers of predefined provinces along the Road receive a passive boost to their castle, city and temple holdings. They can then build trade posts on land, which can be upgraded to make the Silk Road worth even more. However, if a war breaks out and a part of the trade route is caught in the conflict, the trade will be cut from that province and onwards (in a east-to-west direction) for that branch. The trade will instead go through any other branch and result in them receiving more of the trade than they normally would.
- Tributaries: new diplomatic relationship for nomad states forces defeated enemies to keep the Khan’s coffers filled. Tributaries pay a monthly tax to their suzerain and cannot refuse the suzerain's call to wars.
- Larger map: the Central Asian plains are expanded, with 27 new provinces in 8 new duchies and 2 kingdoms, and associated cultures (Uyghur, Khitan, Sogdian and Tocharian) and character history. The size of the base map remains unchanged, as the added counties were previously wasteland.
Additional changes include:
- Government type is no longer determined by the type of capital holding, but more persistently linked to a character. Governments can have various rules that override those of religion (raiding, concubines, etc.)
- Rework of portrait frames to clearly distinguish between the various governments.
- Only the ruler, the Marshal and characters appointed as Commander (a new title) can lead flanks. Vassal levy regiments can still be led by your loyal vassals, but a character can never both lead a flank and a regiment.
- More convenient Honorary title view.
- Serious optimizations to the speed and memory usage of the game.
- Targeted decisions on holdings and titles, via right-click menu (ex: "Make County Capital").
- Merge of Independent Realms map mode and Direct Vassals map mode, using ^Ctrl + Left click to break up a realm into its sub-realms.
- New concept of geographical region, used for localization (hunting a tiger in India or a deer in Europe)
- Forts as an additional holding type (similar to Trade posts), which can be built quickly and cheaply to help with attrition and make reconquest more difficult.
Modding has also been improved with:
- Systematic usage of folder based loading for all common scripts.
- Consistent handling of files loaded from folders: changes are now always added to the modded entity (e.g. a culture or an on_action field), rather than replacing it.
- Custom triggers and effects that can be easily re-used elsewhere.
- New government system allowing to override or add to the special gameplay rules of religions and cultures.
- Nomads are not generated if Horse Lords expansion is not active, contrary to previous expansions where locked government/religions were still being used by the A.I., even though the player could not play them.. This prevents the issue of making unplayable some areas that could previously be played without the DLC.
- The DLC allows nomads of all religions to be playable as non-Christian nomads are the norm rather than the exception.
- One performance improvement of patch 2.4 was regarding huge Byzantine empires in late game, which were slowing down the game because each Greek person was evaluating against each other person in the realm "can I castrate?". 70% of the AI demands were about castrating or blinding someone.