影响力是八大列强独有的游戏机制。列强可以影响那些不是列强的国家，将他们纳入自己势力范围，或是排除出其他列强的势力范围。势力范围会自动地按照外交界面设定的优先级投资到相应的国家上。
影响力将在所有被设定了优先级的国家中按权重分配，低优先级国家1倍权重，中等优先级国家2倍权重，高优先级国家3倍权重。你积累的影响力可以用于不同的外交行动，最终目标是将国家加入你的势力范围。
请注意，如果只有一个国家被设定了优先级，那么无论优先级有多高，它都会被分配所有的影响力。同样地，仅把两个国家都设为高优先级和都设为中等优先级，效果也是一样的。影响力每天都在产生，如果没有任何国家被设定优先级，影响力就会平均分配给世界上的所有非列强国家，这和浪费无异。因此大国总是应该至少影响一个国家。
影响力竞赛
影响力会基于外交界面设定的优先级自动投资到对应的国家上。
当以下情况发生时，你无法对一个国家投资影响力：
- 你的大使被另一个和你竞争的列强驱逐（通过下文列出的外交动作）。
- 你与目标国正在交战。
- 你与目标国之间有停战协定。
在这些情况下，目标国会被影响力机制忽略。所以你的影响力并没有浪费掉，而是投资在了其他国家上。
每日影响力的基数是+0.25，但是目标国会对影响力产生各种各样的修正。这些修正是叠加的，所以-50%修正和+75%修正的最终效果是+25%。当你在目标国拥有了100影响力之后，进一步的影响力投资将用于减少其他竞争列强的影响力。如果所有其他列强在目标国的影响力都是0，并且不对目标国设置优先级，那么你投资的影响力就浪费了。
影响力修正
- Power: The percentage of the influencing nation's total score that it is higher than the target nation's total score is given as a bonus to the influencing nation. This has a maximum +100% bonus, against nations with a score of zero, but can become a penalty in the rare case that a great power has a lower score than a non-great power.
- Vassals: A nation gets +100% bonus to influence with its puppets and dominions.
- Relations: A nation's relations with the target nation is divided by ten and applied as a bonus or penalty (allowing for a maximum +20% bonus, or a minimum -20% penalty).
- Neighbor: A nation that shares a border with the nation attempting to influence it grants a +50% bonus.
- Other Continent: A nation on a different continent than the nation attempting to influence it gives a -50% penalty. Note that it is possible to have both the Neighbor bonus and Other Continent penalty.
- Other Foreign Investors: If a nation has invested in the target nation, a -50% penalty will be applied to all other influencers, unless they reduce the penalty by investing in the target nation themselves. If multiple nations have made investments, each suffers a penalty equal to -50%*(1 - Nation'sInvestment/TotalForeignInvestment). For example, if Nation A has invested £10,000 and Nation B has invested £20,000, then Nation A will suffer a 33.3% penalty, and Nation B a 16.6% penalty. Once a nation is suffering from this penalty, the only way it will ever disappear completely is if the other nation's investment is somehow removed e.g. by the decision Seize the means of production.
- Population: Influencing nations get tremendous penalties in target nations with populations over 10 million (such as China and its larger substates), making them effectively impossible to sphere.
Opinion
Opinion is a measure, separate from relations that ranks how close or far a great power is from adding a nation to its sphere of influence.
The tiers, in descending order:
- In Sphere
- Friendly
- Cordial
- Neutral
- Opposed
- Hostile
Secondary powers that break free of a sphere of influence via the decision Leave Sphere of Influence will immediately drop down to "Opposed" opinion.
If a country has friendly opinion towards a great power and is on the losing side of a defensive war, the great power may intervene in the war. This automatically adds the "Status Quo" war goal and usually causes the great power to become a war leader.
Diplomatic Actions
As you gain influence with a nation, you can use that influence to do the following diplomatic actions. Note that any actions affecting other great powers can only be done if you have equal or higher opinion than that great power(as an example, you cannot discredit a great power that has cordial opinion with a nation unless you also have cordial or higher opinion of that nation). Unlike other diplomatic actions, actions regarding influence to not require any diplomatic points.
- Increase Opinion (50 Influence) - increases a nation's opinion of your nation to the next tier. Also gives +20 relations.
- Decrease Opinion (50 Influence) - decreases a nation's opinion of another Great Power to the tier below. Also gives -10 relations with the great power.
- Add to Sphere (100 Influence, requires Friendly opinion and the nation not to be in any sphere of influence) - Adds a nation to your sphere of influence.
- Remove from Sphere (100 Influence, requires Friendly opinion and the nation to be in another great power's sphere of influence) - Removes the nation from a great power's sphere of influence. Also gives -10 relations with that great power. You can use this action to remove a nation from your own sphere as well. Removing a nation from your own sphere gives you a penalty of -10 prestige and +1 infamy.
- Expel Advisors (50 Influence) - Removes all the influence of another Great Power. Particularly effective if they have a high amount of influence. Also gives -5 relations with the great power.
- Ban Embassy (65 Influence) - Removes all the influence of another Great Power, and prevents them from influencing that nation for 1 year. Also gives -10 relations with the great power.
- Discredit (25 Influence) - Slows the rate of influence gain of another Great Power by 75% (additive with other bonuses) for six months. Also gives -5 relations with the great power.
势力范围
把一个国家加入势力范围可以通过点击 "add to sphere" 这个外交选项来和平完成，或者通过释放国家。也可通过各种战争借口宣战，用军事手段纳入势力范围。 领一个大国可以通过"remove from sphere"外交选项将处在你的势力范围的国家移除，如果那个国家成为超级大国，它也将退出你的势力范围。 一个国家爆发的一场 革命 也将重置国家关系， 并且退出某个国家的势力范围。
纳入势力范围的优点
- If a nation is part of a great powers sphere of influence, a portion of its internal market is joined with its master country and all other members of that sphere of influence, making a larger and more versatile common market. The size of the portion depends on the status of the sphered nation. For uncivilized countries you get access to 100% of their market, for civilized countries 75% and for secondary powers 50%. For civilized and secondary powers, you can increase the percentage by investing in the country.
- Provides prestige when a nation is added to your sphere of influence
- Nations that are sphered are likely to accept all diplomatic requests, such as alliances and military access.
- A sphered nation won't be called into war against its sphere leader, even if it is an ally or satellite of the nation being attacked.
- Enables some unification events and decisions.
纳入势力范围的缺点
- 将国家纳入势力范围会削减一部分关税收入，因为内部交易不需要缴纳关税。
- 有众多手工业者者的国家 (例如中国) 会倾轧工厂，并将这些工厂从市场中挤出。