I propose something like WurmOnline (
http://wurmonline.com/)
(This is how it works in Wurm, not how it exactly should/could be in Outerra):
- Flatten the ground with a shovel. The entire world is made of tiles, if you dig in any spot in the tile (split into 4 squares), that part will drop down a bit; drop dirt to raise.
- Cut down a tree with an axe, cut down the fallen tree with axe in logs, use saw to create planks.
- A whole system of mining and melting to get iron nails.
- Make blueprint of house on the terrain with a mallet; you can place parts of the house on each groundtile, once you're happy you hit "finalize" it. You can't change it anymore now, and you can start constructing.
- With planks and nails in inventory, click on a side of the blueprint with the mallet to build. You can now choose to build a wall, window or a door.
It takes 20 planks and 20 sets of nails to build 1 wall.
Considering you probably won't have deformable terrain (I heard you're interested in implementing it later), the first step will be a bit hard.
Although I do like the blueprint of your house, and then constructing wall per wall.