> 100 simultaneous players visible to each other in a reasonable time but no more; the internet is not fast enough to manage more than that many "people" with

> 100 simultaneous players visible to each other in a reasonable time but no more; the internet is not fast enough to manage more than that many "people" with anything resembling real behavior I participated in a tech demo test about 2 years back, with roughly 3000 players interacting in non-trivial ways (server authoritative). UDP exists. GPGPU exists (NVIDIA helped improve PhysX for this specific scenario). A massive amount of users is not impossible. This MMO does otherwise otherwise impossible.