Block Builder

Build from pieces on stepped ground: draw walls as straight runs, a whole house with the rectangle tool, windows and doors over the walls, fences and paths that climb by ramps; raise, lower and level the land; paint, erase and sub-zone the rooms. Every edit is checked as you drag (red where it cannot go, and why) and can be undone. The pieces, colours and zone kinds are a tool pack's data. Ships empty: a site, nothing built.