This is the game I'm working on currently. I've got all the concepts and ideas in my head and written down; on notepads, napkins, random scraps of paper, etc. The only code I've written so far is the intro screen and basic game play initialization, so my main goal is to get a basic Monopoly game play engine going and then integrate the battle engine and civil management engine into it.
Here's the concept. The piece you move around the board is a scout and you are something of an aspiring ruler. Your goal is to control all the lands through purchasing, trading, and if necessary, warring against your opponents.
Your scout is your eyes, your ears, your diplomat, and your spy. He will let you know how each territory is doing, whether it's available or taken. When he lands on an owned territory, instead of rent, he pays a peace token.
Instead of properties, each space is a territory. The first territory you purchase becomes your capitol. Instead of passing Go to collect $200, everytime you pass the capitol, your fiscal year advances and you collect income from all of your owned territories. Territorial income is affected by the commerce, the culture, the business, and the population levels of that territory. Each territory also has a military force, comprised of all the nifty forces of medieval times.
Monopolies strengthen your fortress strength. All territories have a fortress level 1, but once that Monopoly is formed, they can be upgraded.
Railroads figure prominently in this game because they are the only way to attack territories across the board.
Utilities are also used to support your empire.
