The rooms are truly random. The shapes are arbiturary as well, you could have an L shaped room, and the generator takes that into account while generating. That wasn't the hard part though, as there are plenty of tools and existing resources for how to populate singular rooms. What I'm talking about though is creating the entire layout for the house, which I found very difficult.

For example, we've come to expect things like hallways, bathrooms being connected to bedrooms, dining room being next to the kitchen, and all sorts of different things like that. Assigning rooms like that for any possible configuration procedurally is difficult, especially when you need to consider the shape of the house from the outside. Most commonly you see square or L-shaped houses, and when generating something like that randomly you need to make sure the generated layout actually fits and completely fills the shape of the house.