Multiplayer Guide for Imperator: Rome

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IsaacCAT

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This Opening Post (OP) wants to be a collection of Multiplayer (MP) tips in I:R regardless of any mod installed. The thread is open for discussion about specific mods and I will update this OP with all the suggestions/ideas from players.

POPS

They are the base of every ouptut (taxes, goods, manpower, research points, trade routes). You want to have the most POPs as possible. The quickest way to increase your POPs is through conquest. The second quickest is through enslavement and the third is organic growth.

Non slave and integrated POPs (primary and integrated cultures) contribute to your levies and legions. To increase your non slave and integrated POPs you have two ways:​
  1. Promote your slaves. You want to have around 20% of slaves. To achieve this percentage you need to move your slaves into cities so they are able to promote. To promote faster you want to have as much cities as possible and enact laws that increase promotion speed.​
  2. Assimilate POPs and integrate other cultures. To assimilate POPs you want to switch the governor policy of your provinces to Cultural Assimilation, specially if the province has a majority of POPs from your primary religion. You will want to integrate other cultures than your primary when you have many POPs and/or they give you access to inventions and military traditions from that culture.​
Tax and Trade

Unless you are at maximum research efficiency, you want default taxation. If you are capped on research, it may be wise to switch to Harsh Taxation (Vanilla)

You want to switch to Free Trade as exports always have more value than imports (Vanilla)

To maximize your income you want to have the most surplus of the most valuable goods as possible and export them. Locate where the goods with the best trade value are produced and when you control the territory stack as many slaves as you can to produce the maximum goods. You may want to invest in laws, technologies and buildings that reduce the slaves needed for suplus or right away increase the goods produced.

Do not forget to have markets that buy your expensive surplus goods. If you have surpluses that are not selling you may want to create tributaries or league cities that buy your surplus.

Military Units

At the start of the game you will rely in mercs and levies. Use mercs to assault forts for faster conquest and try to keep levies unscathed. You want to switch to legions as soon as possible.

With levies you have a set of units that is determined by the cultural matchup of your integrated POPs. The same happens with Mercs. With legions you have better modifiers with distinctions and you can choose the unit setup of your army to have the best units possible. Legions can drill and improve their experience, with 100% experience a legion gets a 30% reduction on damage. Drilling legions increases your military experience gain, too.

To decide which unit is best for you, you need to take into account the damage formula factors and the morale number. There are global and specific modifiers for units. For example, for land units, there is the morale, discipline, experience, siege and enslavement efficiency factors that apply to all of your land units:​

1664120188055.png

Ledger : Cohorts​

To decide which is your best unit you need to look at the specific unit modifiers. For example:

1664120308690.png

Ledger : Cohorts
In this setup we can see that units have special modifiers like the attrition weight, morale damage taken and strength damage taken (first column). This special modifiers can very important and define very much the unit. In this case, Heavy Infantry takes a lot more attrition weight than Light Infantry, making it very dependent on supply trains when attacking in territories with low supply. Mounted Skirmishers +25% morale damage taken is a huge modifier that will affect the morale of these units in battle, making them to flee from battle much faster than the other units.

This special modifiers cannot be changed, on the other hand, the offense, discipline, movement speed, defense, morale and cost modifiers that are presented in columns can be modified by technologies and military traditions.​

For land units the damage formula factors are the following:

1664120760402.png

Damage formula​

Because the formula is multiplicative, you want to maximize all numbers at the same time. Explained here:
  • Base Damage: calculated from a roll of dices and modified by terrain penalties (river crossings) and general martial difference. To maximize this factor you need to go with the best martial general possible.
  • Strength: the number of soldiers in your cohort. Maximum is 500 soldiers / cohort. After a battle you can consolidate cohorts to regroup your soldiers but you may lose cohorts (good to do if you are low in manpower) or you want to hit the reorganization button and reinforce your unit up to 500. Ideally, you want to enter battle with full cohorts.
  • Discipline: global discipline + unit discipline
  • Loyalty: if the cohort is loyal to their general they have a boost in discipline. There are some inventions that decrease the chance of this happening. Honestly, it is something that you cannot control, but if you can keep your generals loyal, it is always better to make their troops loyal to your general.
  • Terrain: military traditions give bonus to certain terrains. This number is not shown by the game (vanilla) but you can go through all your military traditions and write down where you have a bonus so you can always choose to do battle in that terrain.
  • Versus: This is a factor that affects units against other units. It cannot be changed and if you know that your enemy has some type of units, you want to counter it by using the best versus possible. Beware that the way the game presents this number is misleading. For example:
1664121310068.png
1664121334607.png

Versus factors of HI and Skirmishers​

Looking at the Heavy Infantry (HI) versus against Skirmishers +5%, one could think that HI is a good counter against skirmishers. However, you need to take into account the factor of skirmishers against HI, that is +20%. The resulting factor is not good for HI, as every turn, HI will deal 1.05 damage but receive 1.20 damage from the skirmishers. I suggest you recalculate all the unit tables in Vanilla or any mod you are using by simetric Versus factors. In this case:
UnitHeavy InfantrySkirmishers
Heavy Infantry1-15
Skirmishers+151

  • Offense vs defense: this factor can be very strong, specially if one player does not use maximized units. The resulting factor when unit 1 is attacking is Unit 1 Offense - Unit 2 Defense. When Unit 2 is attacking, Unit 2 Offense - Unit 1 Defense. As you can see, you want to maximize both offense and defense always.
  • Tactics: this is a bonus you get when you have a countering tactic to the other player tactic and it is bigger as it matches your units. We will talk about how to always get the best tactic in the Tactics and Terrain Chapter.
  • Experience: it has an initial value that decreases in time. It helps reducing damage taken in combat. You can increase experience up to 100% by drilling legions for a reduction of 30% damage.
1664121995114.png

Experience effect​

It is clear that a player that wants to deal as much damage as possible to their enemy will want to switch to legions and choose the best unit with the best specific unit modifiers that he can achieve. In Vanilla it is possible to have discipline, offense and defense modifiers around 60% each that nullify the effect of versus or terrain modifiers. This means that a player that maximizes a unit this way will want to have a legion with only that unit.

Finally, morale. After damage is done, morale is calculated using the following formula:

1664122312456.png

morale formula
The important factors for land units are total damage (calculated before) and morale. Thus you want to maximize damage and have the highest morale possible.

If player 1 has lower morale but bigger total damage than player 2, the result will be more casualties to player 2 but player 1 losing the battle because his units will have lost all their morale. This can be used in a war of attrition if player 1 knows that player 2 has lower manpower pool.

Military Traditions

As seen in the previous chapter, you will want to find the shortest path to:
  1. Get the military traditions that maximize your units damage
  2. Levy size multipliers to increase the fraction of POPs integrated (non slaves) that are mobilized in levies or legions
  3. Special unit abilities like "enable military colonies", "slave raid", etc...
Plan before unlocking the military traditions. You have to decide your bests units depending on your starting culture and the cultures that you think will be able to integrate to unlock their military traditions. Your objective is to maximize one unit offense, defense, discipline and optionaly morale modifiers.

As an example, this is the table of two nations that have unlocked most of the military traditions in the vanilla game for all cultures:

NationMilitary Traditions and trade goods bonusGlobal MoraleGlobal DisciplineoffensedisciplinedefensemoraleStrength damage takenMorale Damage Taken
BactriaArchers
8,85​
66,42​
40​
10​
10​
0​
30,00​
BactriaCamels
8,85​
66,42​
15​
10​
0​
10​
BactriaChariots
8,85​
66,42​
0​
0​
15​
0​
BactriaHeavy Cavalry
8,85​
66,42​
50​
40​
40​
20​
BactriaHI
8,85​
66,42​
85​
50​
45​
30​
-10,00​
BactriaHorse Archers
8,85​
66,42​
20​
25​
20​
20​
25,00​
BactriaLight Cavalry
8,85​
66,42​
35​
5​
20​
20​
BactriaLI
8,85​
66,42​
55​
30​
50​
30​
-30,00​
BactriaElephants
8,85​
66,42​
0​
20​
20​
10​
-50​
20,00​
EgyptArchers
9,68​
57,75​
0​
10​
0​
0​
30,00​
EgyptCamels
9,68​
57,75​
0​
20​
0​
0​
EgyptChariots
9,68​
57,75​
0​
0​
0​
0​
EgyptHeavy Cavalry
9,68​
57,75​
50​
40​
50​
20​
EgyptHI
9,68​
57,75​
95​
50​
55​
30​
-10,00​
EgyptHorse Archers
9,68​
57,75​
10​
25​
0​
10​
25,00​
EgyptLight Cavalry
9,68​
57,75​
60​
20​
40​
30​
EgyptLI
9,68​
57,75​
80​
40​
75​
30​
-30,00​
EgyptElephants
9,68​
57,75​
10​
10​
20​
10​
-50​
20,00​

The Versus table in the game is the following:

VERSUS TABLEArchersCamelsChariotsHeavy CavalryHIHorse ArchersLight CavalryLIElephants
Archers
0​
-10,00​
0​
-10​
10​
0​
-10​
25​
0​
Camels
10​
0,00​
10​
-20​
-10​
10​
0​
10​
-50​
Chariots
20​
-10,00​
0​
-50​
-10​
-50​
10​
35​
-50​
Heavy Cavalry
50​
20,00​
25​
0​
-10​
0​
20​
25​
-50​
HI
0​
-10,00​
25​
20​
0​
-25​
-10​
20​
0​
Horse Archers
25​
-10,00​
25​
-10​
25​
0​
-10​
25​
-20​
Light Cavalry
25​
0,00​
25​
-20​
-50​
25​
0​
25​
-50​
LI
-10​
0,00​
-10​
-25​
-20​
-50​
0​
0​
-20​
Elephants
50​
-10,00​
50​
-10​
40​
-10​
-10​
30​
0​

Using both tables you can calculate the resulting damage of EGYPT vs BACTRIA - BACTRIA vs EGYPT for all units:

BACTRIABACTRIABACTRIABACTRIABACTRIABACTRIABACTRIABACTRIABACTRIA
RESULTING DAMAGE EGYPT vs BACTRIA - BACTRIA vs EGYPTArchersCamelsChariotsHeavy CavalryHIHorse ArchersLight CavalryLIElephants
EGYPTArchers
-0,96​
-0,72​
-0,57​
-3,74​
-2,99​
-1,53​
-1,68​
-1,69​
-2,13​
EGYPTCamels
-0,46​
-0,25​
0,16​
-2,86​
-2,72​
-0,50​
-0,89​
-2,07​
-1,32​
EGYPTChariots
-0,77​
-0,81​
-0,32​
-3,40​
-4,22​
-2,24​
-1,50​
-1,68​
-2,48​
EGYPTHeavy Cavalry
2,72​
2,64​
2,92​
0,11​
-1,64​
1,36​
1,92​
0,93​
-0,20​
EGYPTHI
2,19​
2,69​
4,00​
2,10​
0,30​
1,17​
2,59​
2,04​
0,64​
EGYPTHorse Archers
-0,19​
-0,42​
1,34​
-1,94​
-1,52​
-0,65​
-1,41​
-0,15​
-1,02​
EGYPTLight Cavalry
1,75​
1,52​
2,12​
-1,02​
-1,80​
1,73​
0,86​
0,19​
-0,38​
EGYPTLI
1,59​
2,78​
2,37​
0,14​
-0,72​
0,51​
1,88​
1,00​
0,66​
EGYPTElephants
1,46​
1,24​
2,06​
0,39​
-0,26​
0,59​
0,87​
0,25​
0,01​

As you can see, the unit modifiers from military traditions are very powerful. The Egyptian HI is able to have positive trades with every Bactrian unit no matter the versus table. This is possible because the Egyptian HI has +95 offense and+55 defense. Against the Bactrian HI with +85 offense and +45 defense, the Egyptian HI deals 0,30 more damage in every trade. Considering that global Bactrian discipline is +9 that of the Egyptian, the advantage of unit modifiers is very clear.

Inventions

TODO

Forts

Forts are a powerful defensive deterrent but cost you money.

There are three type of players:
  • Defensive type that combines forts with ramparts and makes the best forts,
  • Average player that keeps one fort per bordering province
  • Agressive players that erase all forts and rely in a strong army to defend their nation.
Forts are required to allow recovery for your troops after you have lost a battle. You need to fall back behind a territory with a fort so the enemy cannot reach you and completly destroy your demoralized and depleted cohorts. For this reason, forts should be in choke points and in layers.

You can bypass a fort by conquering the territories that are next to it, so staying behind a fort is only a temporary solution.

Forts become more interesting in the late game when you need to control the province to feed your armies. Without controlling the fort, you risk running out of supplies while you chase a retreating army.

Supply

TODO

Tactics and Terrain

TODO

Big Battles

TODO

Laws

TODO

Diplomatic Stance

TODO

National Ideas

TODO

Wonders

TODO
 
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IsaacCAT

Field Marshal
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After playing some games in MP I am under the impression that I:R is a fast paced, very round up engine for multiplayer games. These are the lessons from seasoned players that I have been learning and I thougth It would be nice to post them in the forums for all players to discuss and use as a reference.

I will try to update / complete the opening post with my experience and with the discussion in this thread.
 
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IsaacCAT

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I have updated the OP military units chapter, explaining the different factors of the damage and morale formula to decide which are the best units to use.

I have also added the chapter Big Battles to explain in detail how to manage your armies in big battles to recover morale and keep fighting for longer.
 

IsaacCAT

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Updated military traditions tips with objectives and tables calculating effect of unit modifiers on the total damage formula with an example.