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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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From Brown's Warship Losses of World War Two, 200 warships were sunk by mines, compared with 263 by surface action, 330 by sub torpedo and 561 by air attack. Of those 200, 79 were DDs (or HoI4-worthy TBs) or above that were not sunk by friendly mines.

@podcat. In the light of these numbers (axe99) - please (!), do not forget the submarine attack issues!
 
I don't get it. Would someone kindly explain the joke?

Some people assume that the only reason for not showing the designer yet is its apperently unfinished state.
Podcat denies the accusations and hints at revealing it at a later stage for other reasons, most likely the marketing strategy is to slowly build up momentum instead of showing off the best pieces too early.
 
So, in essence, this was merely a clever ruse to introduce MS Minesweeper to the game...

*narrows eyes*

Well played, Paradox, well played...
 
Laying mines is a very good idea for the game. Dont do to much of this stuff (types of mines and so on)

But in my opinion it should have diplomatic trouble. Especially for the nation that start the mine war.

And think if a small nation like Oman blocks the "Red Sea" with a huge mine field while at war with other small nation like Yemen. What would the rest of the world do? Trade around africa? Hell No.

There must be an act of balance and consequences .......

And please never forget: Mines dont know friend / neutral or foe ....... I hope the dev team is checking out in wich way a more diplomatic realism can be in the HOI4 game. That would bring balance especially in huge multiplayer sessions.
 
@podcat

Since @Axe99 beat me to the forums, not much else to say, but HOLY CRAP! Completely unexpected depth being introduced to the naval game. Well over a dozen DDs to go. After this expansion, I doubt you'll ever hear anyone say "Well, in Grigsby's they do...." :) Naval might actually might climb out of 3rd place (compared to air and land), where PDS has kept it since the birth of HOI.

If MTG makes playing the naval side more fun than air or land for naval enthusiasts, mission accomplished!! Heh, makes me now want partial AI enabling for the human player ala HOI3 (although that was theater based for all forces), so I can tell the AI to run my land and air war, while I play only the navy!!
 
So now all we need is a custom GUI mod adding minesweeper into the game and we're set.
 
Are you guys going to add Naval Jet Aircraft? The F-9 was a Naval Fighter, and the F9F was a Naval Fighter Bomber. I'm also wondering if there's going to be Jet icons, like for the P-80 and F-86?
 
Mines are cool and all but really hope they address the low number of naval leaders in the game. They need more naval leaders.