The biggest thing to consider is the generation part itself. How would you create the landscape data before adding the bricks? You could go as far as Dwarf Fortress and Minecraft, and have some fany generator for the surface and then add caves and caverns as well, it could be as simple as choosing a random value for each cell in a grid tat extends one unit past the desired terrain in every direction, and then the individual heights are averages of the bordering 9 cells, it could be layered perlin noise (that one's great if you want to be able to infinitely expand at any time)...
Ask 10 people to create a terrain generator, and you will have 10 completely different results, most of them fairly decent.
Unless you were thinking of something where a person would design the terrain, and not procedural/random generation?