Missions are tasks that can be completed for certain bonuses and rewards ranging from claims and pops to special modifiers or even gaining or releasing new subject nations, providing optional direction for expansion and development as well as flavour and a historically-based narrative for countries that have more unique missions. Some missions, especially timed ones, can trigger events and some can lead to long and complex event chains with many different possible options and outcomes. All missions are structured as part of a mission tree, with prerequisites that enforce a natural flow through the tasks or mutually exclusive paths to force the country to choose between different options as well as optional branches that can be completed for additional bonuses or ignored if it does not the fit the country's current goals. Some mission trees, particularly the generic ones, are highly versatile with the tree structure and task targets dynamically generated to fit the country and region's current circumstances. The current mission tree, or the mission queue if not mission tree is currently selected, can be seen and interacted with in the 
Missions screen.
National Missions
Certain countries have their own dedicated sets of mission trees exploring their culture and history, current situation, and specific ambitions. These are by far the most detailed and fleshed out mission trees, and all require a certain DLC to be enabled in order to appear ingame.
| Countries | Mission page | Mission trees | DLC required | Notes |
|---|---|---|---|---|
 雅典 |
Athenian missions | 4 |  Magna Graecia |
|
 迦太基 |
Carthaginian missions | 10 | File:The Punic Wars DLC.png The Punic Wars | |
 伊庇鲁斯 |
Epirote missions | 3 | File:Epirus DLC.png Epirus | |
 罗马 |
Roman missions | 9 | File:The Punic Wars DLC.png The Punic Wars | |
 斯巴达 |
Spartan missions | 4 | Magna Graecia |
|
 叙拉古 |
Syracusan missions | 4 | Magna Graecia |
Culture Missions
Hatched countries either only have group missions without a particular DLC, do not start with access to the missions but can gain them by becoming independent, expanding, or creating a local formable nation, or potentially have access to multiple group mission trees. Note that this map is not completely comprehensive and it is possible for other countries to gain access to group missions under some circumstances.
Countries of certain culture groups have specific "group" missions, which are available to all countries of the culture group in a specific region or area.
| Culture Group | Mission page | Mission trees | DLC required | Notes |
|---|---|---|---|---|
| Hellenistic | Greek missions | 4 | The minor tags of the Greek 'regions' of the western Mediterranean, Magna Graecia, Greece, and the Black Sea have a single mission tree each. |
Generic Missions
- 主条目：Generic missions
There are 3 generic missions available to all countries in the game:
- The Matter of "Region" - the generic conquest mission directs the country towards the conquest, integration, and assimilation of a neighbouring region.
- Pearl of [Region]/Growth of [Region]/Stabilize and Grow [Region] - the generic infrastructure mission leads to building up and improving the infrastructure, economy, and productivity of one of the country's regions.
- Tribal Reform - the tribal reform mission allows a country to reform from a tribal government form into either a monarchy or a republic.
Mechanics
Mission Tasks
Potential
Not all tasks will always appear in the mission tree, particularly for the generic conquest and infrastructure missions. Mission tasks will only appear if their potential conditions are fulfilled, usually corresponding to if the particular branch was selected or if the task is at all relevant. Some tasks are mutually exclusive with each other, with only one out of a possible set ever appearing at a time depending on the exact circumstances (or possibly being chosen randomly). Tasks whose potential are not met do not appear on the mission tree screen and cannot be completed; if they are listed as a prerequisite for another task, this requirement is instead ignored.
Prerequisites
Other than a few starting missions, most tasks have prerequisites that need to be completed before they can be taken or completed, indicated in the interface by an arrow going from the prerequisite to the task that it unlocks. For the purposes of proceeding along the tree, prerequisites also count as completed if they have been bypassed or do not meet their potential (therefore not appearing on the tree at all).
Bypassing
Tasks can be bypassed under certain conditions, usually either the task requirements no longer being possible or relevant, or a mutually exclusive path being taken. Bypassed tasks can be easily identified by their statue icon being replaced with a heap of rubble; when bypassed, a task is considered completed for most intents and purposes (in particular for the purposes of prerequisites) except that the country does not get the task's rewards.
Completion and Effects
When a mission's requirements are met and its prerequisites have been finished or bypassed, its tile in the mission tree screen will turn from grey to peach and can be taken simply by clicking on it. Most tasks will complete and give their effects immediately, but some missions are timed tasks (indicated by the progress bar at the bottom of the tile) which may take anywhere from a few months to up to two years. Timed tasks may trigger effects when they begin and/or end and frequently have special events that can trigger while they are running as well, and do not count as completed until it has run its entire course. Typically, only one timed task can be running at a time, though instantly completed tasks can still usually be taken while another task is running. A few timed missions can fail under certain circumstances, which stops the progress timer and may prevent the country from retaking the task, blocking them from going down that path.
Mission Trees
Generation
While many of the more country-specific mission trees are largely fixed, the more generic ones are more dynamically generated with different branches and tasks as well as the regions, provinces, or nations they target being selected either randomly or based on the country's current circumstances. Some of the higher-level target selection, such as the region target of the generic conquest and infrastructure missions, is done on potential when the mission first appears in the selection screen; this will not be reset unless the mission is taken and completed or aborted, or if the country no longer meets the requirements (and it therefore loses it from its pool) and then somehow regains it. Most of the lower-level target selection, such as the conquest targets for the generic conquest mission is instead done on start, i.e. when the mission is selected and started. Once a mission is generated and started, it will usually not change the composition of its structure or the target of its tasks while running.
Selection
Each country can only have a single mission tree active at a time. When first starting the game, or after completing or aborting a mission tree, the country will be presented between a choice of up to 3 possible mission trees to take, drawn from the pool of mission trees for which it meets the requirements; nation or culture-specific missions are more likely to appear than generic ones, though it is rare that a country will be eligible for more than 3 mission trees at a time. Each mission can be selected to display a description and a brief overview of the goals of the mission, and then started with the Start Mission button. The available missions are redrawn from the pool each time a mission is completed or aborted, making it possible to take and then abort a mission if the desired mission is possible but does not currently appear. Newly available missions will also automatically appear in the pool after a few days if the country previously did not meet the requirements for any mission trees at all.
Structure
Most mission trees are structured to have a generally linear flow from top to bottom, with at least some of the missions in each row required to start the ones following, with the final completion tasks at the bottom of the tree. Some have varying degrees of branching where the country may be able to choose from a number of different options and outcomes to focus on, with some being mutually exclusive and bypassing the other possible options. In addition to those required to progress down the tree, there are also often many optional tasks and even entire optional branches that do not need to be completed in order to finish the tree, but may provide extra bonuses if the country takes the additional effort to complete them.
Completion
All mission trees have certain final tasks, usually those at the end of the main branch, that need to be completed before finishing the tree; the possible final tasks can be viewed by hovering over the greyed-out Finish Mission button, and they are invariable mutually exclusive if there are multipler possible finishers. Finishing the mission tree can be done at any time after any single final task is completed be pressing the button, which may also give some additional effects or rewards. Waiting to finish the mission tree, for instance to complete various optional tasks, is allowed. Most mission trees can only be taken once and will disappear from the pool forever once completed, though some are repeatable and can be taken over and over as long as their requirements are met.
Abortion
Mission trees can be aborted at any time using the Abort Mission button, and some missions will also be automatically aborted if the country no longer meets certain requirements, though this is generally rare. Aborting a mission tree will prevent the country from proceeding down any remaining tasks, though most currently collected rewards and modifiers will usually be kept and the country will be allowed to select a new mission tree in the mission selection screen. Some missions, particularly the generic conquest mission, also have a cost to aborting that makes extensive use of mission abortion to get the desired target less viable. Aborted mission trees can generally usually be restarted from the beginning if the country still meets the requirements, though most have a cooldown of 20 years after aborting before they can be restarted.