One rule that ran through all the Monopoly pitches I've worked on was that all of the building designs had to decrease in oppulence and size as you make your way around the board away from the Boardwalk. In addition, the designs had to work with the game mechanic of filling a property with houses until the player upgrades to a hotel. Each rectangular property was split into 4 even pieces and each building had to fit in one of the quarters. Other than just vertical scale, the number of levels to the house as well as the inclusion of porches and patios were used to show wealth. One of the ideas put forth early in conception was the idea that plant life was a precious commodity in the future and so only the richest people have yards and foliage on their property. To fit with our modular design style, we designed all our buildings as fully self-contained terrariums. To create a little variety over the course of eight designs, I ended up putting little gardens and grottos on different floors to vary up the design.