Second Life, pre alpha (aka LindenWorld) Aug 2001
Andrew Linden and James Linden managed to get a build running of Second Life circa August 2001. They called it “LindenWorld”. Their first human-like avatar was called “primitar”. Previous versions had used spaceships and flaming eyeballs as avatars. This was one of the first builds that allowed user-created objects. Of course, there was no inventory to put them in, and any other user could modify them. Remnants of the previous ecosystem are here, including rocks, birds, “ators” (snake-like creatures), rain and deformable water.