I plan to do something like this, but not actually use the Blockland name unless somehow I get it from Badspot.
Somewhere around here there's a thread describing my attempts in Unity and Unreal, I've got the general idea of how the building system would work code-wise, and I started working on some stuff in Unreal to move blocks around but I never got them started attaching because I didn't know the structure of Unreal too well
Considering how many projects you burn through I don't think anyone takes you saying that seriously.
If someone like Zeblote, Compmix, Trinick, Trigun, Port etc said they were building it - I might actually get excited.