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HOI4 Dev Diary - Mines and Minesweeping

Welcome to another glorious Wednesday! Today we are going to be talking about mines and mine sweeping. Historically hundreds of thousands of mines were laid during WW2 and with Man the Guns you too will be able to do so in Hearts of Iron.

From a gameplay perspective mines do a lot of interesting things. They add more interaction with the naval layer of the game, create a weapon both for smaller naval nations to fight bigger ones, and for big ones to try and limit where the enemy can get to them.

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As you may remember from my presentation at PDXCON, I talked about adding a ship designer to Man the Guns. It is not quite ready to show off, but it’s important to know that sweeping and laying mines are something you will be upgrading or redesigning your ships to be doing. Minelayers and Minesweepers are not actually new ship classes. In my screenies I have destroyers that can both lay and sweep mines for simplicity, but as @Archangel85 pointed out earlier “I am probably going to have a ton of different destroyer designs”... anyways, details on the designer is for a future diary when it is done, but hopefully it helps explain some stuff in the proper context.

Mines are unlocked from techs and require ship designs fitted to deploy them. Destroyers and light cruisers can do this, as well as submarines with the correct tech (excellent if you as Germany want to make things even more dangerous for the British at a lower risk to yourself). Mines can also be dropped from the air with later game techs. Both of these unlock new missions for navies and airwings.
mine_techs.jpg


Mines can be made better and better through research. You start off with Contact Mines to unlock them. Then their destructive power is improved with Magnetic and Acoustic mine techs and finally with Pressure mines. At the bottom (heh) you also see two techs for submarine mine laying. The first is just the basic ability, while the second improves efficiency a lot by allowing mines to be deployed through torpedo tubes, thus no longer requiring you to design specialized minelaying submarines.

To get rid of mines you need minesweeper capable ships. This unlocks the naval mission to sweep mines and will slowly work at clearing areas. Minesweepers are also nice to include in your fleets as they will then be assumed to travel ahead of the fleet and reduce the impact of mines on them. I suspect a good design combo will be anti-air and sweeper on screen ships to be your passive defense when in enemy waters.
mine_report_map.jpg


There is also a passive “degaussing” technology that can be researched after Magnetic Mines. This was employed during WW2 to reduce the magnetic signature of ships and thus make them less likely to set off mines.

It is also possible to sweep mines from the air, but this is a late game, expensive technology and unlocks a new air mission for bombers. This was something that was done sparingly and in shallow waters, but for example was successfully done to evacuate the Dutch royal family to Britain.

What do mines exactly do then? Well they blow stuff up! Their explosive results are shown on map as accident reports, and there is a new tab too under the Naval Losses statistics interface if you want to dig into details. As ships operate or move through a zone they will risk running into mines. This can lead both to minor damage as well as outright sinkings. The best ways to avoid this is to make sure the area is swept free of mines, but as mentioned above, having your ships travel with sweeping capable ships makes it safer for all.

mines report.jpg

This is not all through, mines have several passive effects.

Naval superiority - Having mines in an area helps amplify the effects of your navy (after all they can concentrate more effectively knowing where the mine fields are). This can be seen in our new naval area screen, which is the naval equivalent of the state view:
travel.jpg


Other than that and blowing ships up mines will slow down enemy ships (since they need to be more careful) and increases the invasion penalty to coastal area. So mines are both good offensively and defensively.

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Mines can only be laid while at war and will start to disappear over time once a nation is completely at peace. You always know how much mines there are in an area, so you know how to deal with them and take them into account. That means that with the new naval access controls you can tell your ships and convoys to avoid heavily mined areas, but of course this may make it a lot more predictable for your enemies where to hunt. Having an advantage in the encryption-decryption war will also add a certain amount of passive defense against mine effects as you may have some information about their positioning.

See you all next week for more Man the Guns info!

Rejected Titles (for extra good reason this time...):
- This War of Mine
- Vengeance is Mine sayeth the Lord Admiral
- Do you mine’d
- This feature was made in cooperation with the seagulls from Finding Nemo
- Mine = blown
- The Ship Designer isn’t unfinished, it’s just a bit shy
- Minesweeper 2000 Online HD Edition
- Mine over Matter
- Mine the guns
 
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I can't wait though I suspect the AI will abuse this to an unrealistic degree.
The a.i. is what you're worried about regarding mine spamming?

I bet you that mines are the first addition to mp house rules. People are gonna abuse the crap out of those mines.

PDS has to find a sweet spot of diminishing returns for mines. It has to be tied to mine decay also in war time.
Ideally some mine laying should be more cost efficient than no mine laying. However, a ton of mine laying needs to be cost prohibitive and the answer again is mine decay.
 
So... on a balance note for multiplayer. All i am seeing in my mind is the allies filling the entire pacific with mines for when japan joins the war. Japan not beeing able to intercept this befor hand or lay their own mine fields will be horrible for them. Not to mention if mines are super effective at attritioning navys and slowing naval invasions. Mind you, the pacific theater is already fucked because it is impossible to take any islands with any half decent player(thinking of Australian divisions with 2k deffence and 1k soft attack) sitting on the ports clicking last stand. Anyways, just my 2 cents, not that it will mean anything
 
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My fear is that adding mines and fuel is going to make a lot of micromanagement. Please reassure me that this is not the case.

Thanks
I hate micro so much that I always go laissez faire in Vicky2.
That said, I'm not worried in the least bit that mines will become a vintage PDS micro nightmare (like whack-a-rebel, HoI2 spies...).

On the contrary, mines are a strategic fire and forget action (or at least can be without too many disadvantages).

You're the UK: you will probably pick a couple of mine regions that won't change during most of the game: Eastern North Sea, channel, biscay, Mediterranean, chinese sea and some more.

Then what? That should be it. Just have one dedicated mine laying fleet for atlantic, pacific and med.
 
Will we be seeing land mines in the future? They were also an important part of the war.

Minefields were always part of larger defence lines, which also included trenches, bunkers, gun emplacements, tank obstacles, etc.
So we already have that in the game as Land Forts and Coastal Forts.

Besides, minefields weren't as big a problem as heavy fortifications. The Maginot Line, Atlantikwall, sieges like those in Sevastopol etc. were all far greater obstacles to advancing armies. It's one of the reasons why light tanks were phased out from frontline duty and everything moved towards heavier tanks with bigger HE shells that could destroy concrete or even armoured fortifications.
 
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I've been thinking about the mines feature and here's a thought. I think mines need to be categorized in a more in depth way. Just having vague mines in a huge sea zone doesn't make a lot of logical sense because realistically you would expect all important waterways to be mined. So, I think intentionally placing mines should equate to heavily concentrating/mining an area.

For example, we could have ocean mines, coastal mines, river mines (if we had navigable rivers), port mines, canal mines, strait mines, etc. This way you have more control if you desire. Also, once you pick an area to mine you would also pick the level of mining that is done. For example, light, or moderate, or heavy, etc. Light mining would be much cheaper, but less dense and less effective. This way you could really decide what waterways you want to concentrate on and mine them in an affordable way for your limited resources.
 
This looks really good, and is something I've been missing for a very long time :) Now if you can just add fast attack torpedo boats (like the S-Boot, MAS, PT etc) this DLC will be absolutely perfect :)
 
Mines are a more timely topic than you might think ...

Unexploded ordnance floating near Brownsville Marina

http://mynorthwest.com/1093945/unexploded-ordnance-brownsville/
Great photo in that article.

It happens here in Britain too often. Recently we had a German sea mine wash up not far from our new Queen Elizabeth II carrier which was in port, you can imagine the jokes that were made out of it :p apparently these are still as dangerous as unexploded bombs dropped from aircrafts.
 
Will planes be able to go on missions to lay minefeilds? I am thinking of aircraft like the Fw 200 Condor

From the DD :)

Mines can also be dropped from the air with later game techs

I'd imagine the He-111 laid more air-dropped mines than any other German aircraft, although that's a guess, but mines were laid from all sorts of aircraft, at all sorts of times (prior to the US Fast Carrier Task Force's raid on Ulithi in the Palau Islands, they dropped mines from Avengers at the two entrances/exits to the lagoon, to stop ships escaping!)
 
(I prefer LF later in the game once my states have the right factories in them.)

I guess that I love the feeling of being a puppet master. Although given the IQ of my capitalists, more often than not I feel like this guy:

images
 
Will-Rogers.jpeg
 
So... on a balance note for multiplayer. All i am seeing in my mind is the allies filling the entire pacific with mines for when japan joins the war. Japan not beeing able to intercept this befor hand or lay their own mine fields will be horrible for them. Not to mention if mines are super effective at attritioning navys and slowing naval invasions. Mind you, the pacific theater is already fucked because it is impossible to take any islands with any half decent player(thinking of Australian divisions with 2k deffence and 1k soft attack) sitting on the ports clicking last stand. Anyways, just my 2 cents, not that it will mean anything
It's a potential problem but as Japan you could work around it by not finishing China super fast, then you'll be able to do the same. We'll see how it behaves.