All of these problems are being addressed in the next update. Although, China building a faction in that way is intentional, as they're roughly even when fighting NATO, Mexico, and North Africa.
It's possible that you're having supply problems. Money is needed to attack, and if you run out, you will loose every battle. This scales with the number of divisions in battle. Try building more factories.
The biome you're fighting on can also add modifiers to attack / defense. Check to see if that's causing problems as well.
The AI nations do not ignore manpower constraints, they just deploy more divisions when you declare war on them, as you can as well. Economy does matter, it's required to resupply divisions. Divisions will wait to go into a battle unless they are fully supplied, otherwise nothing will happen (as per why the units have movement lines but don't damage each other). You can refer to the tutorial for more details.
I do agree with you however that this is not communicated well outside of the tutorial, so I will work on improving that.
The game starts paused, is it possible that you haven't changed the timelapse speed? Press either +/- on the keyboard or on the top right of your screen.
I haven't tried, however, russia does have the most overpowered defensive terrain on the map, so that may help when whittling down white russia.
Also, civil wars only start if your ideology does not match the nation you are trying to become, so you can skip it by changing your country to being communist first.
The regions are all represented by one large dictionary where the first element is a unique color associated with that on the region map, the second is it's location on the map, and the third is a list of every region which that region connects to. It works to be a very rudimentary way of implementing a graph data structure.
Each region has a culture associated with it. When you annex a region, it checks the culture of that region and adds it to a dictionary which every country has with the key being the culture, and the item being a list of all the regions the country owns with that culture. From that, you can get the region ids of each region in a province by just getting the item associated with a certain key within the country class.
I released a day one patch yesterday, so this may already be fixed if playing version 1.1. If not, could you let me know what you were doing when this happened?
It's possible that it's an issue with your antivirus. Conveniently, the sequel, Spirits of Steel: A New Dawn was just released, so maybe you can try that? https://gavgrub.itch.io/sosand
