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RPM-HOI4 logo.png

Major Overhaul

v0.93 for HOIIV v1.9.3

Steam workshop


RPM for HOI4 is an update of the original Realistic Progression Mod (RPM) for HOI3. The main purpose of this mod is an expansion of the available models, equipment, and units for naval, air, and land forces while otherwise staying true to vanilla HOI4.

The mod expands models and units through expanded tech trees and equipment that are common to all countries, though with historical models for all nations where applicable, and generic models where no historical model existed. There is also some rebalancing of combat stats and improvements of historical accuracy for OOBs and the like.


  • This is an extensive mod of the game and is therefore NOT compatible with most other mods.
  • This mod should be playable for 1.9.3 both with and without the Man the Guns and La Resistance DLC (though most balancing, testing, etc., has focused on the version with DLC included).
  • Updated mod to 1.9.3.
    • minor updates from vanilla patch 1.9.3
    • rebalanced some ship, SPG stats to be consistent with 1.9.3 patch
  • Added in RPM version of scout planes (new models, stats, starting techs).
  • Added scout planes to some OOBs.
  • Streamlined armored car stats to be more consistent with new LaR models.
  • Changed later-model CV slots so deck vs. armor is more of a tradeoff.
  • Updated USA CV Ranger Class to carrier_1 hull.
  • Revamp of AI prioities to fix timing of Danzig and other invasions.
  • Revamp of some AI research and div templates.
  • Updated loc and some pics for minor's air units.
  • Added in some missing icon gfx.
  • Various bugfixes and improvements to stats, balance, gfx, etc.

Expanded Naval Techs and Models[edit]

  • New Naval Units.
    • Escort Destroyers (DE) (slower, cheaper destroyers for either convoy escort, torpedo boat roles).
    • Heavy Destroyers (DDH) (generally larger, stronger destroyers).
    • Light Carriers (CVL) (smaller, slightly slower, but much cheaper carrier).
    • Large Submarines (SSL) (larger, stronger, and longer-range submarine).
    • Small Submarines (SSS) (smaller, short-range submarine, good for coastal patrols and minelaying).
    • Cruiser Submarines (SSC) (very large, long-range submarines with scout plane capabilities; same as in vanilla but now with multiple hull models).
  • Expanded Tech Trees and Module Choices.
    • Additional hulls for all units, with consolidation of some hulls as subtechs of their main hull types.
    • New naval module techs: many modules have one or more additional tech years for more flexibility in ship design. There is also a new heavy-medium (10"-12") gun battery, differential CV decks (early, improved, advanced—for more planes) , regular and heavy minelaying equipment, and cruiser armor specific to heavy cruisers.
    • Restructured module slots for hulls makes it harder than in vanilla to make ahistoric meta ship variants.
  • NEW! Historical Existing and Decision-Based Ship Variants.
    • Historical existing models at start-up plus an expanded version of the RPM-TWAS Historical Ship Variants mod (made specifically for this mod. This adds over 160 historical ship variants for the 1936+ unlockable through decisions.
  • Additional Naval Modifications.
    • NEW! Rebalancing of naval IC production caps (now 5 NIC for smaller ships and 8 NIC for capitals).
    • Revised effects of naval terrain and night combat gives more realistic combat balance.
    • Rebalancing of combat and production statistics, including an across-the-board reduction in fuel and IC costs.
    • Revised AI ship design that allows AI to script historical models better than in vanilla.

Expanded Air Techs and Models[edit]

  • New Air Units.
    • Multi-Role Fighters (twin-engine escort fighters with considerable ground support ability, particularly later in the war).
    • Heavy Fighters (redesigned to have role of a heavy fighter-interceptor and/or fighter-bomber).
    • Night Fighters (twin-engine fighter specializing in interception).
    • Light Bombers (hybrid between CAS and a tactical bomber).
    • Heavy Strategic Bombers (heavier, stronger, and costlier strategic bomber).
  • Expanded Tech Trees.
    • Significantly expanded models for all units; there now is a serious trade-off between switching to producing a new model vs. upgrading an existing model.
    • New air component techs: Ground Support Weapons, Drop Tanks, Bombs, Air Search Radios and RADAR, and Air Navigation Equipment.
    • Rebalanced combat and production statistics, including more relevant statistics for CAG models (i.e. CAG CAS now a true dive bomber, CAG Naval now a true torpedo bomber, Naval bomber now more of a patrol bomber).
    • Completely rebalanced variant upgrade statistics (upgraded aircraft are now across-the-board better than baseline models).
  • Historical Models for the Major Nations.
    • Historical models (both produced and designed) for all major nations.

Expanded Tank Techs and Models[edit]

  • New Armor Units.
    • Infantry Tank (slower tank, somewhere between a medium and heavy in size, that specializes in infantry support).
    • Armored Car (recon/support vehicle that is fast and slightly armored but otherwise weak; later models pack a bit of an anti-tank/hard attack punch).
  • Expanded Tech Trees.
    • Significantly expanded models for all units; there now is a serious trade-off between switching to producing a new model vs. upgrading an existing model.
    • New tank component techs: Guns, Armor, Suspension.
    • Rebalanced combat and production statistics, and some rebalancing of variant upgrades.
    • Some lesser-used units got the axe (SPAA, Super Heavy Tank), and SPGs and TDs are realigned to be mostly a mid-war addition.
  • Historical Models for the Major Nations.
    • Historical models (both produced and designed) for all major nations.

For All Models[edit]

  • Upgrades are now initially cheaper (because more models are always better in RPM!).
  • Some rebalancing of XP gain, XP costs, experience losses.
  • Updated OOBs, ship variants, air units (with names!) and starting techs for all nations as well.


Many thanks to darthkommandant for his New Generals mod [Note: will be added back once it’s compatible with 1.5.0 again] and Better Kreigsmarine Ship Names mod, which are now included. And special thanks to CPack for ALL of the great air model pics!!! And special thanks to www.tanks-encyclopedia.com for all of the great new armor pics. Finally, many thanks to Axe99 for all his help and his sharing of work from The War at Sea mod, and to Ogima, Papa Joe Stalin, and the rest of the team at the World War 2 Simulation Mod for all their collaboration and promotion of this mod.