I think this novel came out in the 2000s. There are many cultures that live close together but are very different, for example some pretend to be pre-industrial. One of the main characters is a youth who grew up in a pretend pre-industrial society and is now exploring the rest of the solar system? ring-world?
Each culture experiences their own reality that is defined by a ruleset. One of the rulesets becomes aggressively self-propagating and this is the problem that drives the plot.
At some point a tumbling house, just a normal house, is used to travel across space.