Hm, here are a couple of ideas that I think could be beneficial for a sequel.
- Ability to create different types of militia/infantry/whatever with experience levels. Have a huge difference between building/training a green anti-partisan 'police force' and a regular, full-strength infantry division.
- Partisans. Absolutely have to represent them in some fashion. Also, specialized anti-partisan units.
- Ability to have units have a task or order. Nothing complex, but 'guard x province', 'move to x', 'quell partisan activity' (chance for a division to find and kill partisan cells in adjacent provinces), etc.
- Diplomatic deals with countries. Say I'm Japan. If I think that Siam will ally with us, I could make a deal: x resources/units (as exp. forces) in exchange for tech. Or even, ask for military access in exchange for resources/tech.
- Killable leaders, but with the ability to create new leaders with a specific rank and level, but at cost of manpower or similar abstract variable, with random traits possible. Ex: I could order up a leader that's a Major General skill 1 and it'll take x manpower and x days, but it would take years to create a Field Marshal of any skill, or a General above skill 0, etc. Time and cost related to how many units the leader can command and it's skill. And, traits completely random (and more of them), like in Victoria.
- Being able, as a neutral nation, to request a nation to join a local alliance, or request that they join a war against a nation or alliance. Think EU2 with the ability to specifically request nations to join a war. However, a nation can't create a local alliance if they're in one of the Big Three, and if the leader of a local alliance joins a Big Three alliance, each member can decide to join the big alliance or become neutral again. This would allow for better ways to simulate events like the Winter War.
- Ability to auto-assign leaders to individual divisions as soon as they are deployed which would be handy for large nations. The AI will assign Mj. Generals to divisions newly deployed or without leaders, if possible (as the leader pool allows). You could also tell it, "assign leaders with skill >= x", or "assign leaders with trait x first".
- Ability to design units, when the tech for the unit is first researched. This is completely optional, and if the player doesn't want to, the default stats are used. The AI will, unless specified in the scenario or AI file, will use the default. Note that designing a unit will increase significantly the cost and time to build that unit.
- Some internal political matters, like implementing loyalty to leaders and ministers, conducting purges, dissent from rationing goods if CG is within x% of the minimum to be out of the red (one time only), etc.
- For the love of decency, no sudden end to the game when your nation is annexed! Put the player in a hands-off mode or something, no fog, and if they want to, they can continue to watch the game (and save and continue watching!), being able to view everything (foreign ministers, units, tech trees, etc.). Or, the player can set up a message box such that when his nation is annexed, the game pauses and a message box pops up, with the same effect as the 'End Scenario' button in the endgame message. But please, don't just dump the player back to desktop!