After addictively playing around with this scenario for a month, I have included a list to my own tweaks-as in the alliance system-to what I would like to see done in future versions (I am willing to donate my time).
1: Break apart the tech tree. I would divide it into the default four sections, where there is a few supertechnologies that stores improvements and units. It would also allow the tech tree to be cleaned up a little bit.
2. Create paths for technologies instead of years. The player, and AI, should have their own warfare priorities. There is little reason for the Soviets to develop sea technology; similarly, the Germans did not develop the same productivity base that the Americans had. Thus I recommend that the tech trees be split up into four branches: Army, Navy, Air Force and Internal Improvements.
3. City specific wonders: I'm not sure the civ engine allows for basically unlimited strategic resources, but it could add a new dimension for seizing specific territories. For instance, Coal Plants might require coal. Why? Certain Industries and means of production can not be too far away from where they're built. This way, a Manhattan project might be required to be built near a resource of Heavy Water or Uranium. It could also mean that "French Conscription Plants" could be built that produce infantry every turn they exist (Though make one citizen unhappy). This will fit into the "Tech Tree" very well, as you can potentially have a city to produce a bunch of units every turn if you research that line of the tree.
4. Create an invisible partisan unit with the ability to pillage. Its importance will be shown with...
5. All bonuses to terrain should be by worker improvement only-unimproved terrain provides no value. This will allow strategic bombing to be in the game again. Mining, or industry, should be very expensive and produce shields only. Similarly, fields for food should only produce food. The only units that should be able to pillage should be specified, as partisans, SS Infantry, etc.-this would make the German war against the Soviet Union far more interesting. This would make countryside improvements more important than city improvements for production anyway. Make all terrain improvements far more expensive.
6. Make German units stronger, fewer, and more expensive, and allied units cheaper and weaker. There's a saying that it took five Shermans to one tiger-but the Shermans could be produced very quickly. Similarly, the Russians could replenish their forces very quickly, but the Germans could not. Thus cheap Russian arms-and not good ones-would slow down the Germans and eventually defeat them. I've also heard from seniors complaints about the quality of some American equipment, especially compared with German equipment-and a lot of Russian Equipment I've heard very bad things about, despite the fact after the war some have been glorified (I won't go into that now). Also, this would justify the generals of the German Military and not Hitler; the generals wanted to occupy the urban and industrial bases, and Hitler wanted to destroy the army, and this had a major flaw; the Russian army was nearly endless. Also tons of weak Russian units with ability to pillage roaming around the Russian countryside can make the German war effort very difficult (especially if tanks can only go on squares with roads, this might make them useless-as historically they had become).
7. Create a Spanish frontier with France, with strong defenses on both border, as well as surrounding Gibrater with strongpoints from other nations. This forces an amphibious assault on it, or an invasion of Spain.
8. Bangkok always gets burned down when I play.
9. Enslave units; all units create POWs; all civs (In particular Russians and Germans) could get workers; since the Germans and Russians made them into slaves, they would be slightly faster.
10. Reshape the unit/improvement menu. Keep happiness with happiness, infantry with infantry, productivity with productivity, trade with trade, science with science, ships with ships, aircraft with aircraft, etc. Barracks should be near the Airport and Harbor and Missile Defense. Library should be near Research. This will allow organization, and allow even more units-some obsolete-and far more improvements-without destroying the game.
11. Since the AI wouldn't know how to use most of these tweaks, give the AI tremendous unit advantages. Make money be a problem with the human, but not AI, playing Russia. Make productivity be a problem with Germany. Make happiness a problem with Britain in the empire. Make America devoid of military technology initially, and perhaps productivity, but make roads to factories, science, and money very easy to build, and once America mobilizes, can produce units very quickly (Perhaps "Infantry" plants would be in order, as well as "Sherman" plants). Lend-Lease plants could also (In combination with "Resource required" squares) be built in particular cities only.
12. Give Improvement penalty to mobilization. (Better yet, omit it from the game. It changes the value of too many units productivity-wise).
13. Include weapons never developped (German Propellor Long Range Bomber, American Jet Bomber, Helicopter Transport) or weapons considered but never truly finished (V-3, ICBM, Submarine Aircraft Carriers). Also remove the ability of Germany and Russia to build radar towers.
Longer Detailed Tweaks
14. Detach France from the allied nations. Make France in a locked alliance with Poland, and make the German invasion of Poland optional. Possibly include Belgium, the Netherlands in this alliance; also Denmark and Norway should be in a locked alliance. Personally, I'd make this the alliance system:
Alliance 1: UK, US, China, Persia v. Axis powers always
Alliance 2: France, Belgium, Denmark, Norway, The Netherlands, Poland. The AI should inevitably find itself at war with Germany
Alliance 3: Japan, Thailand, Italy
Alliance 4: Germany
Set Germany's Aggression level very high, as well as Finland (Fortify the Norwegian-Finnish-Swedish border to prevent a war) and make the USSR's aggression level very high, so it might attack Germany, or even Poland or the Allies should the axis not, and invariably Finland; and Alliance 1 should be locked against 3 and 4, alliance 2 should be locked against 3 (Because defeatist attitudes). These mutual alliances, for me, have avoided war between allies, as they're too focused on their enemies. Alliance 2 could, with defeat, reasonably go against the allies. The separation of Italy and Germany is made to allow kind of for Vichy France, while allowing Japan to take over Asia. I would build a tough line for the Germans along the borders of all countries (Anti-partisan) and create several partisans for Belgium, France and The Netherlands; if Germany does not negotiate, they're going to basically have bombed out countries. Germany I don't think should have these partisans though, but rather tough, immobile Volksturm, or however its spelled. Its pillaging unit should be the SS Infantry and SS divisions, which should upgrade throughout the war.
15. Tech Tree Adaptations
Land Units:
I would create three types of paths for the land units
1. Tanks/Anti-Tank
2. Infantry/Upgrades
3. Artillery
4. Special Ops
I don't think this scenario shows just how immobile the tanks were. Most tanks I would not have, actually, be able to go off of roads, except possibly on flatlands type terrain. I think this would better stress the value of infantry, as only infantry/marines would be able to hold high ground. It would also make roads more important militarily. It would also allow a player to research say, tank development, and neglect, say, special operations (Commandos, Marines). It would also allow you to develop better marines for an invasion of England once England mobilizes, or it allows England to develop better invasion skills, etc...Infantry transport vehicles can make railroads obsolete, and as the game moves along, they get cheaper, or could move further, but only on roads; this might make railroads obsolete, so you could set new railroads at a tremendous price (1000).
For air force, I would go
1. Bombers
2. Fighters
3. Jet Craft/Missile Technology
4. Anti-Aircraft
5. Atomic Development
Jet Development should actually be held separately from then conventional aircraft. Why? Because it was underdevelopped before the end of the war, for a few problems. Stalin jailed most of the Russian Air Designers who experimented with what would become the jet engine in the 1920s and 1930s. Hitler was also demanding of a fighter-bomber, preventing use of the Me-262 until 1944. Furthermore, though air to air missiles were equipped on the FW 190, they were unreliable and easily jammed, yet the Me 262 ran too fast to accurately shoot down other planes. By the end of World War II, the Germans had developped a supersonic stealth bomber, which was to go into service in November 1945. Inclusion of the Ho-XVIIIB and Ho-XIIIB models would be the ultimate bomber in the game, and theoretically, equivilents should be availible to the US if they pursue this technology. Anti-Aircraft would include newer Flak/Anti-Aircraft, until SAMs are ready. A stealth missile equipped fighter would also be virtually indestructible to propellor aircraft as well.
Navy
1. Aircraft Carrier (Get better defense and cheaper)
2. Battleships (Offense and speed-but get obsolete earlier)
3. Submarine Technology (Offense and speed, and eventual bombardment)
4. Submarine Defense
5. Cruisers/Destroyers/Flotillas
The Germans would start here with submarine technology. The British with Battleships, etc.
Improvements
1. Civil Defense/Anti-Tank
2. Productivity
3. Workers (Better productivity as game progressives, also can move two squares per turn later)
4. Culture/Happiness/Revenue/Science
I think that certain improvements should be given at default-Temples, Light Factories, perhaps medium factories, marketplace, airport, library. I think better research programs could be researched, and faster workers/worker upgrades researched. The Russians/Americans would clearly have better productivity than the Germans.