• there's, at most, two players waiting in the lobby at a given time.
it makes no sense to allocate more than two seats since the threadsim
will consume them whenever they are ready to join the party.  i'm
thinking of using channels to synchronize the two threads, so
threadsim doesn't loop doing nothing (but sleeping) until at least a
couple of players join.

• the integrator has to operate with vectors and the different objects
in the universe, some of which may require their own governing laws.

• think of a way to pack the bullets efficiently.  will they be part
of the global state broadcast?  what does the client need to know to
render and manage them?

• it could be beneficial to do dynamics in the client as well, which
means sending more data, and probably require a tighter sync, but a
smoother user experience.