Somewhat related to this is the Reserve status of your troops: not only can you build Reserve units (reduced strength at ratios determined by Laws, but cheaper to build) you can then Mobilize them at a later date to bring them up to full strength this is an excellent way to build-up divisions and brigades during peace time. Also some of the Laws only become available when certain conditions are met – can’t shift your economy into a strong war footing until you’re actually at war. Politics, Laws, and Ministers: with the new Laws it is much easier to change the direction of the country – no more of the only-one-change-per-year ala HOI 2. A good example of this is shown in the 1936 Germany start, as aero-related tech is somewhat strong on the theoretical but little or no practical experience the research times for aero-tech are long until you can use your air force against Czechoslovakia and then Poland you’ll notice much shorter duration for tech researches at that point due to all of the practical experience gained. Back to the Tech: there is both a theoretical component and a practical real-world experience component that affect research time. The sliders are still there, but they can be automated and are more 'intelligent' this time around.
Example: if you complete the Light Tank Armor tech your Light Tanks toughness, defense and speed (more armor, slower unit – at least until you upgrade the engine) will upgrade as long as you have enough allocation in the Upgrade slider. Which leads to Upgrading - once the tech is done to the unit it will only upgrade that part of the unit. The Tech tree is more realistic and more HOI 1-ish no more having to upgrade Infantry, Mountain, Paratroop and Marines individually - in HOI 3 once the infantry weapon or support tech is researched it is applied throughout your infantry units likewise for some tech in armor, aero and naval. I myself only played one ‘vanilla’ game of HOI before falling for the mods, and I don’t plan on reverting back. Check out the Paradox Interactive Forums and see what’s out there.
Like the earlier game releases the game is highly mod-able and there are some very good mods created so far that can add flavor and playability - things like SS units, new techs and specific country techs, and many more historically accurate Events. It is a 'world war' it should be complex - go play Axis and Allies if you want a simple and fast game of World War II.
It is also MASSIVE and very intricate some may find that intimidating but I relish it. Once that technical is done, the game play does take a while before it becomes intuitive, but it does take the better aspects of the two earlier games (I liked the tech tree of I, and the control of II) and tries to make it work.
Being a fanboy of HOI 1 and 2, I am somewhat disappointed on the release of HOI 3: it is pretty much given that you have to patch upgrade to 1.4 right from the box.
Players can ask the improved AI to handle tasks both large and small, while a new economic model allows for overseas weapon procurement, and the expanded intelligence system offers gamers more ways to learn about enemy reserves and troop movement.
There are 20 brigade types to deploy, a dozen different technology trees, and thousands of real-world military commanders and politicians available. However, decisive shifts in world power are often most dependent on military action, and Hearts of Iron III addresses this by giving gamers the option of controlling their armed forces from a broad perspective in the form of battalions, or all the way down to an individual soldiers. Players take control of any nation that existed during the time period of 1936 to 1948, and then try to fashion themselves into a world power through a combination of military might, domestic production, research and technology, politics, and diplomacy. Paradox Interactive's critically acclaimed strategy series returns in Hearts of Iron III, this time offering grognards more than 150 nations to control and more than 10,000 provinces to manage and conquer.