Q: Can special factories build only one type of equipment?
A: No. They don't build any kind of equipment. Instead, they reduce production cost of associated equipment.

Q: Does building special factory reduce equipment cost of linked type?
A: Yes.

Q: What is the max level of bonus for special factories?
A: 20 is the last level.

Q: Why is there so many different kinds of equipments?
A: BICE is a mod of much complexity aiming to make gameplay as close to real life as possible. And in real life, leaders had to worry about a lot of different equipment.

Q: Why I can't research any tanks and/or airplanes and/or ships?
A: The nation you're playing has it's own, unique tree for that equipment.

Q: Can I research/build/use unique tanks and/or airplanes and/or ships of other countries?
A: No you can't, if you get unique tanks/planes/ships from other countries you won't be able to use them either.

• Up to 10 support companies in a division instead of 5.
  
• Green highlight of selected units in army view. <<< The most important of all changes.
  
• Division template/designer screen been changed. (stats are shown below instead of to the right)
  
• Minimum required training increased to 40%.
  
• Generals max division count lowered to 16.
  
• Possible naval dockyards in ship production line limited to 4.
  
• Possible military factories in production line increases to 16.
  
• Max civilian factories working on a construction increased to 16.
  
• Expanded production screen to hold 2 columns.
  
• Justifying war goals costs hell of a lot more political power.
  
• Increased justification time reduction based on world tension.

<work in progress, for now will only be some basic information as stats will change a lot>

• Infantry
  Equipment: Infantry Equipment, Uniforms/Boots/Helmets
  General purpose infantry. If you need more information, play vanilla HOI IV before jumping into BICE.
  
• Militia
  Equipment: Infantry Equipment, Uniforms/Boots/Helmets
  Very low training time, low stats and organization battalion. Higher AA attack. Extra defense in forest, mountain, urban, jungle and marsh terrain. May be used: to form some defensive line very fast as they can be deployed after 8 days in training, as military police - it has the same suppresion as normal infantry while being much cheaper, or as a cheaper version of infantry. Keep in mind they cost more manpower.
  
• Garrison
  Equipment: Infantry Equipment, Garrison Maintenance, Uniforms/Boots/Helmets
  Higher defense, quite good AA attack. Slightly cheaper to produce than normal infantry, also take only half as much manpower. They lower breakthrough - if you add them to normal division those will be less effective in attack. Almost as long training as ordinary infantry. Defense is their only use - militia is more effective at being police. I recommend keeping garrison divisions in separate army/armies from your offensive divisions.
  
• Light Infantry
  Equipment: Infantry Equipment, Light Infantry Equipment, Uniforms/Boots/Helmets
  
• Mountain Infantry
  Equipment: Infantry Equipment, Mountain Equipment, Uniforms/Boots/Helmets
  
• Naval Infantry
  Equipment: Infantry Equipment, Naval Equipment, Uniforms/Boots/Helmets
  
• Paratroopers
  Equipment: Infantry Equipment, Paratroop Equipment, Uniforms/Boots/Helmets

Mobile

• Cavalry
  Equipment:
  
• Semi-motorised Infantry
  Equipment:
  
• Motorised Infatry
  Equipment:
  
• Mechanised Infantry
  Equipment:

IMPORTANT: When I talk about "upgrade" techs, I mean tech that give immediate bonus to all connected units, without the need of producing new equipment.
If I don't mention something, it's because it hasn't been changed in BICE.

• "Support Equipment" upgrade path has been split up into 2 parts: "HMG" and "Mortar". Unlike in vanilla where each level gave the same bonus, in BICE every next level is more important than previous. HMG is giving higher defense, while mortars give the same bonus in defense & breakthrough.
  
• "Uniform" is completely new type of equipment, used by all infantry, motorized & mechanized battalions(support units don't seem to use it, with exception of Div. HQ). Important thing here is, even only researching next level gives bonus to recovery rate. On top of that, 2nd and further levels of uniform have 2 defense instead of 1, and recovery rate increases on each of them by 0.10. And because cost of producing it doesn't increase, you might as well change to them.
  
• "Sniper Team" is a single-level upgrade tech giving 3% defense to all inf&mot&mech. Small bonus, smaller than in HMG or mortar techs, but it might give you the edge or at least lower your casualties when winning.
  
• "Explosives team", similar to snipers, is a single-level upgrade tech, increasing anti-tank capabilities, as well as greatly increasing attack in urban & fort areas.
  
• Anti Tank. Instead of 2 upgrade techs for inf&mot&mech techs, there is now 1 upgrade-only tech, and 2 techs both unlocking new equipment(1st equipment is used by AT guns, 2nd is rocket artillery) and upgrading inf&mot&mech.
  
• Motorised. "Semi-motorised", "light truck transport" and "truck transport" equipments have been added.
  
• Special units. BICE adds light infantry and commandos. On top of that, there are some specialised support units: urban, desert, naval, mountain, airborne and jungle. Both new special units and support units require specialised equipment.

• New types of recon companies have been added - cavalry and motorcycle. They use their own special equipment, and give higher movement bonuses to division than standard recon companies. But they seem not to be affected by recon company reconaissance upgrades, while same upgrades linked to them benefit normal recon company.
  
• Flamethrower squads. Unlike in other mods where flamethowers are upgrade for engineer companies, in BICE flamethrower is it's own support-only batallion, giving great bonuses to attack in urban, fort, forest, marsh and jungle areas.

All units here use specific equipment, and each tech unlocks new level of that equipment.

• Armored Cars. Support-only company, giving some reconaissance and movement bonuses.(similar to motorcycle recon)
  
• Tankettes. Support-only companies, giving your division some armor and quite a lot of breakthrough. Looks like they don't affect hardness though.
  
• Liason vehicles. Used by HQ companies. Higher levels increase it's speed and reliability. Cost remains the same.
  
• Transport half-tracks. To be honest, I still haven't figured out how are they used. I think they're the same as mechanized equipment, but I'm yet to confirm that.
  
• Light, medium, heavy, modern, and super-heavy tanks have not been changed.
  
• Cavalry tanks. Between light and medium tanks. Probably to be used as medium tanks until you research those.
  
• Infantry tanks. Between medium and heavy tanks. Higher defense than heavy tanks but lower offensive capabilities. When you need some more armor/hardness for divisions but not necessary need more firepower. Much cheaper than heavy tanks.

Some major coutries have their own, unique tech trees and can't research generic tanks(still can research everything in the upper part of armor tech tree). Those tech trees are shown on the left side of technologies screen. German tank tree for example:

• Anti-air and anti-tank have gotten heavy variants. Heavy variants are available as support companies only. They use specific heavy-types of equipments. Right now there is a bug with last levels of those so I'd recommed avoiding them.
  
• Artillery has been split into 5 types - mountain, light, medium, motorised and heavy. Mountain, light and medium artillery use horse transports, motorized uses truck transports, and heavy uses prime movers.
  
• Coastal and railway artillery. Those are 2 new unit types with specific equipments. Important things to know: Coastal artillery is veeeeery slow. It has -500% speed modifier on all terrains. Railway also has a big penalty to speed, -112%, but it's in jungle only, on other terrains it's between 5% and 12%.

• From new ships, there is a new "legacy ships tab". These are just weaker & cheaper versions of ships for poorer countries.
  
• What is more interesting, there is quite a lot of upgrade techs for ships now. Those are pretty self-explanatory though and I won't explain them here. Just remember that they affect all ships including those that are already deployed.

I won't be explaining special factories here, those will have their own section made.

• Something I'd call education branch. Those are techs similar to vanila tools improvements. Just beware that last tech in it, "Foreign Labour" is giving a lot of negative modifiers for only 5% factory output. It gives quite a lot of recruitable population though, so I would only take it when you desperately need more manpower.
  
• Concentrated/Dispersed industry. Other than unlocking techs related to special factories, there have been some major changes here. All levels of both branches reduce recruitable population by 1%. First 2 levels of concentrated industry are considerably weaker than dispersed, but from level 3 they are better again.
  
• Construction now affects only build speed of civilian factories.
  
• Defenses & infrastracture & civilian technologies. Those are pretty self explanatory. Few things to note though: "Civilian woks" techs increase number of civilian factories used on consumer goods. Even though there is no shown link, to unlock any of those techs on higher levels, previous level has to be researched too.
  
• Resource production. Steel mills have been added - they produce 8 steel. Oil & rubber have been split into 2 building. You unlock rubber at 3rd level of synthetic oil research. Oil refinery gives 5 oil, rubber refinery gives 2 rubber.

After researching and building special factories, you will get a cost reduction bonus based on how many factories of that type you have built.

None of the special factories are able to produce equipment - they are used only to reduce equipment cost.

Keep in mind that this bonus DOES NOT increase with every factory built, instead it increases when you reach a certain number of factories.

So, for example, 1 small arms factory will give the same bonus as 2,3 or 4 small factories, but the moment you build(or rather get event some time after building) 5th the bonus increases.

It takes some time for events giving bonuses to fire.

Start at 5% reduction, each new one gives very little bonus(even 0.3% per factory) which is increasing on highercount of factories(even 2% per factory), up to 30% reduction at 20 factories.

TO DO

Munitions factories

Uniform factories

They give some nice bonuses to division, including initiative which greatly increases planning speed. I'd say it's better to have them than not.

On top of being used by HQ companies, HQ equipment has one more use, though it's not about using them - exactly the opposite.
The more HQ equipment you have in stockpile, the better bonus for army command you get.
Table with equipment required & bonuses:

First of all, I would like to thank everyone who participated in it for making BICE mod for HOI IV! I know there is still a lot of work ahead of you, but considering you only had 3 months to work on modding HOI IV you did great job!
And another thanks to Panzeroo, for answering some of my questions related to BICE that helped in making this guide.


Just as BICE, this guide too is a work in progress. And I also hope that steam community will help in making this guide as complete as it is possible - both by asking right questions, as well as providing new important information or correcting my mistakes, after all, I am a human being too. Ok, I'm a lemur, so maybe not 'human' being, but you get the point. :)