This system is a new stackable modular building set, the idea being it represents the 'second wave' of colonisation, the first wave being the PUP colony buildings. These buildings are designed to be (only slightly) more comfortable and visually pleasing than the PUPs which are brutally practical, so would typically house the families and more white-collar colonists while the terraformers and roughnecks are stuck in the PUPs until whichever Conglomerate has bankrolled the colony sees fit to upgrade them.
The Mk1 consisted of a stackable core building, a small hab module, a slightly larger shop module, and a lift unit. After time to playtest them and think on it, the Mk2 has been slightly redesigned to be easier to construct and stronger once it is constructed. So far we have the central core which has an optional lift shaft inside it, a larger hab module, and a tunnel walkway that connects cores above ground. The set has been designed from the start to ease certain problems with stackable buildings while offering as many options as possible, and will be expanded over the next month or so until it's ready for release.
Here's a couple of renders of a complex put together just using the basic 3 modules on a square representing a 4'x4' board.