... not released yet)
3. Seme as point 2.. Multithread terrain-rendering, roads on it, and vehicles to go around.
The most important part is terrain-rendering. The Algorithm at the heart of it features my first and second theorem abut polygonal surface approximation. It took something like 2 years to develop it. It's technically a view-dependent, continuous dynamic level-of-detail rendering algorithm. Main features are simplicity and documentation.
Does easily a 4k x 4k terrain, but also much more.