AberMUD
AberMUD /ˈæbərmʌd/ was the first popular open source MUD. It was named after the town Aberystwyth, in which it was written. The first version was written in B by Alan Cox, Richard Acott, Jim Finnis, and Leon Thrane based at University of Wales, Aberystwyth for an old Honeywell mainframe and opened in 1987.