I want to build a world that I would want to inhabit, and I want to earn that world.

Generally, for me, that means starting out with nothing, but having the potential of a utopia, but that's hidden behind a lot of hard work and planning.

I think that the Civilization series has great depth of content, in that it has a massive tech tree and a near endless selection of buildings. However, it lacks depth of gameplay (in base building terms), because the buildings aren't in any supply chains; you just bank until you can build and forget about your building.

A good depth is about finding the right balance between number and types of structures, having appropriate tiers or pre-requisites to construct, and having them interdependent. That interdependency is tough, because some games are quite simple, but others can get so complicated that only the Rainman can keep track of all of them. I think that a good balance is to have just enough interdependency that you can memorize how everything is connected, but just complicated enough that things never work perfectly.

Breadth, to me, is about all the activities you can do in a game. Is it just a base? Is it your base vs the elements and population issues like Banished or Planetbase? Or monsters? Do you need to build an army? Do you need to control that army?

Or is it about personalization? Park benches and fountains? Or will the game so personalized, like Dwarf Fortress, wherein items are crafted with such a convolusion of NPC attributes that they just get lost in all the complexity?

Again, I want to build a world that I want to live in. So, I really want decoration. I just adore Banished with the decorative item mods, because I can take a moment and make the world my own personal utopia.

There has to be a manageable balance of all of these things, but based around a core idea that is fun. Banished is about fighting the elements and supply chains. Planetbase has it's mechanic of domes. Dawn of Discovery/Anno has it's area of influence circles. Then the rest of the game is filled in around that to balance what makes it unique or fun.

And at the end of it all, the absolute key is that I should be able to ask, "Do I want to go live or vacation there?" and have the answer be a "Hell yeah!"