Hmmm, it’s not quite a correct statement, but it’s pretty close. The original LU client still exists, and we have enough data to get them working. Since it’s collected from users, things like Nexus2 or BlastClient came to be, which are just different sets of files of the old client which are usable more or less. The client has all images and assets, models and GUI stuff, which is amazing since we then only have to focus on the missing part: The servers. (Btw, there is LU Rebuilt and another project with a similar name which I don’t remember right now, who are writing a new software from scratch.)

What we do is recreating the servers that LEGO had by emulating the network traffic and data handling that the client requires. This is very difficult, because it involves a lot of guesswork, since LEGO didn’t provide an API documentation for packets. Some developers that were in the early team that developed such a custom server (long before this page or even TTS was a thing, actually even before LU closed) are creating just that at the moment.

The LU models are done in *.nif format of the Gambryo engine, and if I recall correctly, there are some obj to nif converters out there. I might just have been export to obj, not sure about that. But if it’s possible, you should be able to convert from blender to nif, but that really is not relevant now.

LDD is a finished software. Writing it in the first place might be as difficult as writing BBB in LU when the code was done initially, but what we need to do is to find the right packets and the right syntax and data to send to hook into the client part of BBB to make it work. Maybe more form a users perspective: Making the original BBB work is harder than creating an LDD like tool. Maybe this metaphor is fitting (i’m usually really bad at metaphors): We’re not building a ship, we’re trying to recover, fix and sail a sunken ship.