I somewhat fail to see the connection between Roblox and MUDs but FWIW one of the most well known MUDs of the 90's is still up and running, M.U.M.E (Multi-Users

I somewhat fail to see the connection between Roblox and MUDs but FWIW one of the most well known MUDs of the 90's is still up and running, M.U.M.E (Multi-Users in Middle Earth). It was a Diku derivative but with its own online language for the wizards to code in, designed by a compiler PhD, at the time it was state of the art. MUMEs attraction was that it was difficult and run with attention to details and RPG.