User:Tsubakura/Sandbox/Introduction to Node Types and Branching Rules

Last updated: 15-04-2017

Branching rules are one of the most important core components in the game. They basically decide what ships you are allowed to bring into the map and whether the ship combination you are using gives you an optimized route. Everything from strategies to recommendations starts with branching rules, because without branching rules, you do not know what the optimal setups are to reach your goal. Reading a branching rule is easy if it exists... but what if a new event happens and you actually have to chart one out by yourself with the data provided?

This blog serves as an introduction as to the different types of nodes, as well as the different mechanics that lies behind the branching rules. While it is recommended that you should at least know the basics, it is by no means required, as I will include some introductions for those who are new and by some chance, found this blog.

In case you are also interested on how to assist in charting the branching rules yourself, this blog would be a good place to start.

=The Basics= Let's first start with some basic re-cap of the knowledge you should be knowing, if you are playing this game. This includes being able to understand what all the nodes mean on the map and on how to read the branching rule tables that are listed everywhere.

Node Types
All node types except the boss node are initially white, until you have visited that node once. After you re-enter the map, the nodes you have visited will be colored depending on the type of the node, with the exception of blue nodes.

Branching Rule Tables
The next thing you need to know of course, is on how to effectively read the branching rules listed here. While each site has their own design and method of listing the branching rules, the principle remains the same for all of them.

As 1-5 is the first map where fleet specific branching rules are introduced, it would also serve as the best example here to know how much branching rules can affect your progress.

The possible routes
First, you have to determine which routes you can take to reach the goal, which is node I. There are 2 possible routes from what we can see:
 * Route A-B-D-I
 * Route A-B-C-E-I

When deciding on which route is the most efficient, you check all the nodes that all have a branching route in them, which are node B, C, D and E. Of course you should only check the nodes that are relevant to you and nothing else, so let's split this investigation in 2 part.

Route A-B-D-I
Node B is where the first branching takes place, and the branching rule is as follows:
 * If the amount of ships in fleet is ≦ 4, the routing is guaranteed to C
 * Random routing if the amount of ships in fleet is ≧ 5

Which translates to that if you have 4 or fewer ships in your fleet, you will always go to C, while if you have more ships, the routing pattern becomes random. In other words, to be able to reach node D, you are forced into a random routing in which there is a possibility that you might also go to C. So for this route, you have to consider what you should do in case you do get sent to C, instead of your intended route of D, which we will check out later.

Lets check out the next set of branching rules in case you do hit node D:
 * Node H
 * Amount of ships in fleet is ≧ 5
 * Node I
 * Amount of ships in fleet is ≦ 4

Combine that with the information you have from the previous node, it means that you need at least 5 or more ships to have a chance of reaching node D and to reach the boss node, you are not allowed to have 5 or more ships. In other words, unless you somehow manage to sink your 5th ship on node D to reduce your amount of ships in the fleet to 4, getting to the boss this way is impossible. With that, the A-B-D-I route is obviously ruled out.(Adding that I have no interest in advertising strategies which involves sinking your own ships.)

Route A-B-C-E-I
In this route, you will also pass through node B. While having 4 or less does guarantee you the routing to C, you will have to think about whether lowering your firepower justifies you having a guaranteed routing.

However, if we take a look at node C's branching rules, we have the following:
 * Node E
 * Does not meet any of the requirement to go to F
 * Node F
 * Fleet contains (F)BB (BBV does not count)
 * Fleet contains SS
 * Amount of CL in fleet is ≧ 3 (CLT and CT does not count)
 * Amount of ships in the fleet is ≧ 5

This changes quite a few things, mainly the last branching rule. When we explored node B, we had to consider whether using 4 ships or fewer and thus a lower firepower, would justify having a guaranteed routing. However, this is no longer relevant, because the branching rules now clearly states that if you do not use 4 or fewer ships in the fleet, you cannot reach the boss at all.

Continuing on at Node E:
 * Node G
 * 70-90% chance of off routing if:
 * Fleet contains no CVL, AV, LHA or CAV
 * Amount of CVL ≧ 2
 * Amount of AV ≧ 2
 * Amount of CAV ≧ 2
 * Node I
 * Guaranteed if the fleet contains at least a CVL, AV, LHA or CAV and the fleet does not meet the requirements to off route to G.

So from your fleet of 4 ships, you must at least have either a CVL, AV, LHA or CAV in your fleet to guarantee the routing to the boss, or you will suffer a random chance of offrouting to G instead.

Now that we have gone through every node to the boss, we can sum up all the requirements we need to reach the boss. To effectively reach the boss with an optimal setup, we need the following in your fleet:
 * Amount of ships in your fleet = 4
 * Amount of CL in fleet must remain ≦ 2
 * You are not allowed to use any SS(V)
 * You are not allowed to use FBB or BB, but BBV is still allowed
 * To guarantee your routing to the boss, have at least 1 CVL, AV, LHA or CAV, but do not bring 2 or more of the same class. Bringing 2 CVL for example will fail, for example.

While this analysis looks intimidating and long, once you get the hang of it, you probably don't even need this wall of text explanation of mine to properly understand the branching rules. The analysis only looks long, because I have taken into consideration of every possible outcome, which is probably not even necessary and a waste of time to do in 1-5.

With this, you should be able to have a grasp as to how the branching rules are set up. Keep in mind the following few things though when it comes to branching rules in general:
 * Depending on the circumstances, you might not be able to get the most optimal route. Some quests for 1-5 for example, forces you to use 4 DD, which effectively prevents you from using a CVL, AV, LHA or CAV for the guaranteed routing.
 * Using stronger setups will usually give you longer routes, while lighter setups give you shorter routes. In those cases, you have to decide whether having a longer route but stronger fleet is worth the trouble, or that it might be doable with a lighter fleet at the risk of having a higher retreat rate and lower chance of defeating the boss. This is especially very common in events.
 * The best route might not be available to everyone due to not having the required ships or there might not even be a best route at all.

Reading branching rule tables is easy enough, but how about making one yourself? Read on.

Introduction to charting Branching Rules
As someone who has charted the branching rules of the events for quite a while now, I can say that it is quite complex, especially if you have nothing to base your data on.

When starting out, you need some preparations while also knowing the following:
 * Do you know all the branching rule types? This is important as you are usually working from a clean slate during the events. It helps that you know what kind of branching rules exists and where to look for in that time.
 * In light of a new branching rule mechanic being a possibility, do you know where to look at when dealing with weird results? As every event is different, you will always have to keep a lookout on new mechanics that might influence the branching rules in any way. A strong example is Winter 2017 Event, which introduced dynamic routing for the first time.
 * Do you have people willing to test compositions for you? Or do you somehow have access to a large data size, for example? Having people willing to help you out and having a big data size for you to work with is definitely important here. It is also the reason why I have set up google submission forms for people every event, so that I can collect data for everyone to work with.
 * Did you obtain all the information you can get from the historians? As event themes are all related to in real life operations during the 2nd world war, there is nobody better you could ask than the historians. The people of history might know what has happened in each operation to give you an idea as to how the event will go and also importantly, which ships are involved for the historical routing.

Branching Rules
The list will be presented in the following format:
 * Name: The unofficial name which I have dubbed for the specific branching rule.
 * Frequency: How often this type of branching rule is used in general and on which portion of the map it is used usually. Note that knowing this is not important at all, but it is an interesting thing to know regardless.
 * Description: A description as to what the branching rule checks and how it works.
 * Example: An example(s) will be given for the branching rule type

Keep in mind that it isn't strictly one type of branching rule per node. In fact, it is usually more likely that a node consists of multiple types of branching rules.

Frequency
Commonly seen everywhere

Description
The branching rule that checks whether you actually have met any requirements at all to go to a node. In cases where you don't fully meet the requirements to go to any nodes, it will default to either random routing or in some cases, a default route to a certain node.

Frequency
Very rarely observed after first seen in 1-5.

Description
Sets a restriction that checks how many ships you have in your fleet during the sortie. Ironically, while it is introduced first in 1-5, it isn't often used at all after that. It is also most likely contributed from the fact that nobody would intentionally use fewer ships without a good reason.

Frequency
Literally everywhere

Description
Sets a restriction based on the amount of one ship type or a count of multiple ship types added together. This branching rule could force you to have a CL in your fleet, use a certain amount of DD in your fleet, prevent you from using too many BB/CV or even flat out ban the use of some ship types. The count is not restricted to 1 type of ships, it could also be a count of multiple ship types grouped together.

Frequency
Uncommon

Description
Checks whether the required ship type is the flagship of the fleet. The required flagship is usually a CL.

Frequency
Not seen often, but there is usually at least one during events.

Description
This branching rule checks which nodes you have traveled through or on which starting point you have started. Through that method, it will decide which node you get sent to next.

Frequency
Very common

Description
Checks whether the speed of the fleet is Slow, Fast, Fast+ or Fastest.

Frequency
Rarely seen on maps.

Description
Checks whether you have a certain amount of equipment equipped. This could also be a total requirement over multiple ships, preventing you from equipping the requirement total on a single ship. Drums and seaplanes are the most common requirements, but there have been cases of other requirements.

Frequency
Seen often in normal maps, but seen literally everywhere on event maps, especially at the node that is right before the boss node.

Description
Checks whether you have the required LoS in your fleet. A passed LoS check is noticed through a seaplane animation that appears on the map. The seaplane will then fly to the node you are supposed to go and then fly back, your fleet will then move over to the next node.

Frequency
Very rare.

Description
Checks whether a specific ship is in the fleet or not. The requirements can sometimes require you to have her as flagship.

Frequency
Very common

Description
A conditional branching rule that must be fulfilled, before the underlying branching rules can be fulfilled.

Frequency
None in normal maps, but common in events.

Description
Checks what kind of combined fleet has been used to decide which node the fleet goes to.

Frequency
None on normal maps, but there is always at least one during events.

Description
A branching rule that checks whether you have the required amount of ships in the fleet that has historical references to the map theme.

Example
Historical Ships:
 * (F)BB(V):,
 * CV(L): ,
 * CA:, , , , ,
 * CL(T) ,
 * DD:
 * AV: