My humble rip-off of Dwarf Fortress. I'm not going for the same level of complexity. It's a much higher-level, approachable, side view, science fiction themed game. More like a "SimMoon" or something. But there's no doubt in the world that it was entirely inspired by the wonderful Dwarf Fortress.
You are an entrepreneurial space creature who has just been awarded a hunk of rock-asteroid in the middle of space. It's up to you to do something with what you've been given. What that is can depend greatly. Maybe you have to make a profit. Maybe your job is to make the asteroid habitable for colonization. Maybe you have to set up a prison before the transport full of convicts arrive in 5 moon-years.
Whatever your reason, you have landed on an asteroid. All you have is your spaceship with some start-up cargo and some workers. You order around your workers in order to transform the asteroid into something worthwhile. Your little workers can mine, that might be a first step if you want to start building an underground city (as it's cold outside). Workers digs holes into the ground and soon you can build underground complexes and install machinery. You can also build buildings on the surface. If you have the right supplies. As you dig up the ground, you find minerals and stuff you can process into ore that helps you build more.
There is a very important idea of a tech-tree for building and adding to your asteroid. You become able to build new things as you build their dependencies, research into various fields, or buy research.
Eventually, you can turn your asteroid into a bustling holiday location (if you build fun stuff like hotels, zoos, malls, terraforming for breathable-air), spaceport (repair shops, restaurants, trading depots), prison satelite, hospital planet, etc... This makes for easy missions, goals, as well as fun sandbox play. Your limitations would probably be the size of the planet. Someday a metagame could let you manage interplanetary commerce (you develop a reputation as you leave a trail of successfully converted asteroids in your wake), but, bleh. Lets start with digging holes.
Okay, I know they aren't really "user stories" in the XP sense, because they're too big. But I forget what to call these things. They are tiny little sketches of a feature I'd like to put into the game, and how the user interface might look a bit to pull that off.
The following UI have to be in here and pretty solid.