That sounds pretty cool.
Also, who's the other person making a sequel that you mentioned?
I'd rather not say just yet; I haven't seen them post about the project, so they probably want to keep it under wraps for now. I may end up helping them though, especially in regards to maps.
As for my game, I want to take it in a different direction - having it work possibly like a CAD program (similar to SketchUp or Blender). You would have to earn the geometry you build with, which would also be used as the game's currency. You could have a job or business to earn geometry (i.e. selling creations you've made), or harvest it from the environment around you.
By the way, made some progress with the game's building mechanics. I'm trying to make building be as easy and initiative as possible, and will add other shapes you can choose from over time. You'll eventually be able to carve into meshes (to create openings like windows and doorways), add pre-made objects, draw geometry by hand, manipulate objects (via position, rotation and scale), re-texture / recolor faces, etc.
By default, you'll walk around as a player - similar to Blockland, but will be able to move around freely when building.