This is a very interesting game! You can create 3D structures for free. The entire game is free! Existing 3D worlds can be used by all players. For creative minds who are involved in 3D architecture, whether privately or professionally, this offers a very broad opportunity to build, invent or even just test ideas. Programmers who like to programme in C++ will also find a free opportunity here to test or even apply their scripts.
In summary, I have yet to find a better way to get to know the 3D world for free, get creative or just play around on the internet!