Ok, so, some ramblings on my next IOT (Into the Fire, while not finished yet, is approaching the end).
First thought:
Most IOTs focus on expansion = power, in all shapes and forms. There aren't (usually, not always) major focuses on economic force as deriving from such factors as population, internal industry, etc.
So, in this next IOT, there will be a major focus on different types of infrastructure, population growth, trade, etc.
First up: Infrastructure. There will be many different categories, and you can generally put many, many pieces of infrastructure within a province, assuming I can fit it in there on the map.
Infrastructure generally builds exponentially. You can spread it around your nation, which will generally protect it from the various woes that befall a nation, but it works more effectively within a few specialised provinces. (I.E., 3 units of infrastructure in one province are better than 3 infrastructure in 3 provinces, from an economic standpoint).
Next in line: Population
You can't do a ton without people, and, so, population is monitored in-game. GDP per capita is a very important measure of your economy (you can have all the money you want, but if your population is dirt poor, you aren't going to be doing well). Population will be somewhat based off of RL population densities, albeit simplified. Growth and decay are modeled by RNG percentages, which can be influenced by warzones, economies, and other disasters. Higher populations aren't always better, but very low ones usually are a bad thing.
Trade:
A big focus will be international trade. Among other things, you need to be able to reach the nation you wish to trade with, and have somewhere to put cargo. Suddenly, bordering nations, coastlines, and navies have become much more important. Isthmuses, straits, and canals will be very influential in this.
Expansion vs. Infrastructure:
Expansionism isn't always a good thing in this game. For starters, the bigger you get, the more it costs to expand. Additionally, you have to pay upkeep for your existing provinces, which further limits territorial growth.
On the other hand, being an OPM generally doesn't help your cause, either.
Generally speaking, "wide" nations will have larger militaries and more people.
On the other hand, "tall" nations will have better economies and more advanced militaries.
Diplomacy:
To encourage player RP and diplomacy, a UN of sorts will be created. While I am not 100% sure what the extent and limit of its powers will be, it will be able to impose economic sanctions upon other nations.
Obviously, this seems rather vague at the moment. There will be solid numbers at a later date, I'm just throwing ideas out right now. This IOT will have a new map (and a name) before it starts. Comments, responses, etc. are appreciated. Note that the above is subject to change at any point.