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Hi everyone and welcome back to regular weekly dev diaries (if you don't count the april fools one last week). I know you are all super excited to hear what we have been up to since Battle for the Bosporus. The answers to that are going to take a few dev diaries to cover, so I figured I would start with a timeline for you:
  • We recently released 1.10.4 to fix various multiplayer exploits going on, but seems an important case was not detected at the time so we are working on a 1.10.5 to address that soon.
  • Pdxcon is coming up in May so expect to hear some more details there.
  • The yearly anniversary is coming in June so expect some cool stuff and a patch.
  • We are however spending most of our time on the 1.11 Barbarossa update as well as the unannounced expansion that will be released together with it. That's what we will spend most of our diaries on, as well as today!

‘Barbarossa’ and the unannounced DLC will focus on the Eastern Front and the core of Hearts of Iron, which is warfare - particularly land warfare. Historically the Eastern Front was without doubt the most important front for World War II. It was the largest confrontation in history and
is where Hitler’s expansion was first stopped and pushed back signaling the eventual doom of the axis powers. There are several areas we want to improve here. Weather does not feel impactful enough, while historically it had a massive impact. Logistics currently doesn’t have much player interaction and is mostly something you have to deal with only when problems appear, and finally the combat and division meta has been stable (with an emphasis on large divisions) for a long time - something we hope we can shake up. As you can imagine, these are all things that affect the game on a deeper level and take a lot of work to get right.

Today, I’ll give you guys a bit of an overview on the supply aspect, but fair warning: it’s early days and stuff may still change here before we’re done. I’ll probably spend 3+ diaries on supply over the course of the development to cover everything, but I figured it would be nice to hear about the overarching ideas.

The old system worked by having discrete supply areas pathing back to the players capital and keeping track of the bottlenecks. To simplify a bit ;) - those bottlenecks then decided how many units could fit into areas near the front without penalties. The areas themselves were unintuitive to players and required you to check multiple mapmodes to see if you stepped over an edge etc. I do like bottleneck systems though, because feedback is usually immediate, but it suffered from not having much scaling cost as distances increased, so it was hard to use it to limit snowballing. As I mentioned it was also a system you didn't care too much about until you had problems, while historically, logistics was a vital part of planning a campaign. This led to combining the issue with another gripe of ours - that the way fronts moved in WW2 often followed important railroads, but don't really in HOI4. We came to the conclusion that we should try and make a system focused on railways and with a truck based component as a way to get more out of it when away from the rails.

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In our new system, supply flows from the capital (the total amount available depends on your total industrial base) through railways, where the level of the railway acts as a bottleneck. To transport more, you need a higher level railway (or a bigger port if it goes over water) so the railways are the current bottlenecks in a way. Depending on how much supply is transported you need a certain amount of trains for the rails to perform. Trains are a new equipment type that we will dig into in a future diary (well actually, several types ;P)

An important part of railways is that they are capturable, so as you push into enemy territory you will want to make sure to hold vital railways and capture railway hubs to supply your troops. There is a conversion time here to model the fact that there was usually some repair or re-gauging that needed to happen for attackers.

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Mapmodes are still quite WIP ;)

Rivers also had a huge importance on the eastern front for transport and supply so they will work essentially like basic railroads now, where you need to control both sides of their banks to use them to ship supplies around.

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Supply is drawn from what we call Supply Hubs now, which are either cities, naval bases, or manually constructed stations along the rails, which have to be linked into the network. Air supply works a bit differently but we will talk about this in the future along with some other supply additions...

The flow of supply from a Hub to a division depends on the terrain/weather etc, and ideally you want to have available trucks here (which is to say, motorized equipment) to increase the amount of supply you get as well as range. Cost of trucks and trains and losses to attrition and bad weather will be a limiting factor on your logistics.

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Overall, this creates a system where it's strategically sound to fight over railways, prepare for large offensives, to try and bleed each other's logistics capability and to force care when advancing in bad terrain and weather. The result is a much more fun, historical and immersive Eastern Front as well as adding a new layer of invasion planning in the rest of the world.

See you all next week for the next diary!
 
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They were modelled on historical maps (although finding good maps for 1936 specifically was a bit of a challenge, so I had to use maps from the late 20ies and early 30ies). That said, there were a number of creative decisions for the sake of balance and performance. Not every possible railroad was included, and I aimed more for representing the major network layout (so the French network is heavily centered around Paris, for example) instead of representing every railroad ever. For large parts of central Europe, being completely accurate would have meant covering every province with railroads in ever direction, making them somewhat pointless (and more performance intensive as every unit has to constantly calculate which of the hundreds of nodes is the correct one to draw supplies from). We are still tweaking the system though, so we may decide to add a few railways that don't exist in 1936 but would be complete no-brainers to build at the game start to fix glaring supply issues in various places (The Japanese-Chinese frontier is a bit of a problem child in this regard).

In the final resort, if we have to choose between building the entire system around working with a 100% accurate historical setup or adding a single low-level railway somewhere and have it work with an otherwise balanced system, we will do the latter.

It depends. The Autobahn focus does not give you railways, but the Australian and Indian focuses talking about railways do. They either upgrade existing railways or add some in places that I thought it would make sense.

Just out of curiosity, do trucks modify the push of supply to units or are they required for supplying units outside of the general reach of a depot? In the latter case, this could lead to serious problems regarding poorly industrialized nations being unable to effectively supply their troops. Going by the assumptiion that the former model is being used, will theaters be able to choose the means of supply(ie. the use of horses and hoofing it vs the use of trucks)? Will terrain impact the effectiveness of truck based supply?
 
Yes but I don`t really see Italy fitting in this DLC, it would also not make much sense from a selling perspective IMHO. Not sure what the fourth country could be though. Maybe a Scandinavian country?
Weren't the trains Italy's most well-known (propaganda) victory in WWII*? At the very least that should be enough for an achievement.

Trains running on Thyme: as Italy, operate a railway from Suez to Kuwait.

* EDIT: Inter-war era might have been a better word.
 
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They were modelled on historical maps (although finding good maps for 1936 specifically was a bit of a challenge, so I had to use maps from the late 20ies and early 30ies). That said, there were a number of creative decisions for the sake of balance and performance. Not every possible railroad was included, and I aimed more for representing the major network layout (so the French network is heavily centered around Paris, for example) instead of representing every railroad ever. For large parts of central Europe, being completely accurate would have meant covering every province with railroads in ever direction, making them somewhat pointless (and more performance intensive as every unit has to constantly calculate which of the hundreds of nodes is the correct one to draw supplies from). We are still tweaking the system though, so we may decide to add a few railways that don't exist in 1936 but would be complete no-brainers to build at the game start to fix glaring supply issues in various places (The Japanese-Chinese frontier is a bit of a problem child in this regard).

In the final resort, if we have to choose between building the entire system around working with a 100% accurate historical setup or adding a single low-level railway somewhere and have it work with an otherwise balanced system, we will do the latter.



It depends. The Autobahn focus does not give you railways, but the Australian and Indian focuses talking about railways do. They either upgrade existing railways or add some in places that I thought it would make sense.
Are there plans to keep the current infrastructure levels system?

Elsewhere the point has been made that in places with bad infrastructure animals were superior to trucks, so could the levels of infrastructure abstract the quality of roads/small railroads, and the worse the quality the worse range of wheeled transport (while horses would take a smaller hit)? This could also be affected by weather (e.g. Russian muddy season might reduce infrastructure by 3 levels and so make wheeled transport worse than horse drawn transport).

It seems like a good way to keep the new railroad system useful (as that determines supply to a region) while making the quality of smaller lines/roads important (as that determines how far you can go from the end of major rail heads/how effective are trucks/animal transport and which is used).

Maybe infrastructure could even be on a tile level to get more granularity, though that'd be a major pain I think.

Edits to add tile idea.