I haven't played world map since it was released (played a couple of games right after release) but a few things I remember about it:
1) The Chinese are too weak. Japan will basically crush China 99 out of 100 games if they want to, it's not very difficult. Something needs to be done to (in my opinion) deter Japan from trying to conquer China - maybe super partisan reaction, or an event that reduces JP income by 100 every turn that they hold key Chinese cities - something really painful for Japan that causes them to want to avoid entering the interior of China. I'm no expert on the war in China but historically the Japanese were unable or unwilling to advance deep into China. On the other hand we don't want super-China so something has to be done to make it hard for the Chinese to hurt the Japanese much or in particular advance out of China. Maybe Chinese units can all have 1 attack value but high defence values? China should be a distraction for Japan but not a situation that is "winnable" the way it is in this game.
2) The map just seems too small. I wish that the map had double the number of hexes. It feels very strange to be operating with so few hexes on the Russian front, in France, etc.
3) The pacific war felt weird. I didn't see a lot of reason for Japan to advance into the Pacific at all. They seem better off stopping at Philippines and Indonesia and focusing on India and China and Siberia.
The Chinese war is hard to model as a war game because so many aspects of it are totally different to the European war. To list a few:
- Some people try to portray China as a Russia-style meat-grinder for the Japanese but this is completely inaccurate. For long period of the war the Chinese weren't even in contact with the Japanese, and trade went across the front lines.
- Fighting primarily happened whenever the Japanese tried to advance. The Chinese would impose a cost in men and materiel on the Japanese, but more-or-less, wherever the Japanese wished to go, they could get there.
- From 1940 onwards the Japanese were trying to reach a political victory over China. Their goal, per the internal documents produced by Japanese HQ in China, was to replace the Chinese government with a friendly one. They explicitly were not seeking a military victory over the Chinese as they did not want to end up garrisoning more land than they had already. The Japanese army did not stop advancing in '40 because they were stopped by the Chinese, but because they chose to stop. With a brief exception for the fighting around Changsha in '43, this carried on until Operation Ichi-Go in '44.
- Operation Ichi-Go shows exactly what would have happened had the Japanese carried on advancing in '40: they would have swept all before them but then ended up having to occupy more land with all the costs that entailed. In this sense the war in China was essentially unwinnable for Japan - the only way of winning was political but a political victory was out of the question because no Chinese government would make the concessions that the Japanese wanted, since they were effectively the same as colonising China.
- The above goes against the national pride of a lot of Mainland Chinese historians and so just isn't recognised as much as it ought to be. The story of WW2 told in China is that the Japanese were beaten by China pretty much alone.
- For games this makes things difficult to model because either they try to make China a meat-grinder (and the war ends early because neither side can sustain a meat-grinder conflict) or they have to implement a whole bunch of special mechanisms which result in games that are less than entirely fun.
- Making China a meat grinder also inevitably has a knock-on effect on the Pacific War. If China is a meat-grinder then a sensible Japanese player just commits enough resources to win the war and does nothing in the Pacific until its over. No sensible player would do what the Japanese did if they regarded China as a live conflict - but the Japanese did not see China that way.
American Front: a Work-in-progress CSA v USA Turtledove mod for SC:WW1 can be seen here.