A simulation must either provide a complete construction system or make the same abreviated assumptions as above. Coding for flexible colony layout and modular building construction is VERY COMPLEX, dealing with surface deformation, exterior surfaces and details, and the all important interior details, with functional elements such as doors and windows. In addition, a interdependent system that deals with facilities, air processing, water processing, power systems and even biological and medical systems.
Aesthetics are also a necessary element. Again something that is typically dealt with in games that have established cultures and franchise artwork. Think Star Wars or LoTR… all with deep and established cultural and racial systems. For a pure colonization simulation – the architectural consideration should evolve into something that allows a certain aesthetic sufficient to create a comfortable and homely feeling, particularly as the colony grows and brings more village elements into play. The practics will dictate a significant amount of both 3D and 2D artwork asset creation and a complex building and layout system. The alternative (more likely) is an industrial cookie cutter solution, and definately the solution for the initial landing and establishing of a seed presence.
One of the possible solutions is the ability to take apart modules or panels from the landing ship and reconfigure them to create walls, dividers and ceilings. Also the ability to provide or create forms (perhaps out of thin but strong plastics) that would allow a exanded foam solution to fill, would allow a colonist to mass produce building blocks. Having access to a materials that can use the local soil and stone as aggregate would also be an interesting possibility. All of this material must be very lightweight if being ported onsite, even the machines and processors necessary to manufacture.
One must also deal with how these constructs can be sealed from the environment, support the power and data systems, sensors, etc. that tie the facility together.
At odds are the systematic requirements of a database and rendering system and the desire to add creativity and personalization into the system. Player created assets uploaded to a server for validation will require a player tool, standardized to ensure assets are properly optimized for the engine, and typically a large learning curve, as well as additional gaming technology that allows such a mechanism. This also introduces a large variable for failure… both for the server/client engine and for the player who may not properly understand the balance between sustaining systems and living space needs.
For a production simulator, it is likely that massive compromises will be made, but hopefully with enough rational guidance to provide an immersive and enjoyable simulator that will attract participants and provide a compelling experience.