Test networked physics with rolling cube.
Like:
https://gafferongames.com/post/introduction_to_networked_physics/
http://mikolalysenko.github.io/local-perception-filter-demo/
It simulates 2 clients and the server locally. Each client controls a rolling cube.
There are 3 views, 2 client and the server.
Local input is not applied until confirmed by the server.