Reverse-engineering the 1998 Ultima Online demo server

A developer has completed a 10-year reverse-engineering project of the 1998 Ultima Online demo server, releasing approximately 5,000 disassembled functions translated into portable C99 code on GitHub. The demo, which shipped with the "The Second Age" expansion in October 1998, contained actual production server code from mid-1998 running on a reduced map featuring only the island of Ocllo, though many UO server emulators have previously used parts of it without fully reverse-engineering it. The project was completed using recent advances in large language models to assist with the translation process, with each function compared instruction-by-instruction against the original binary compiled with Microsoft Visual C++ 5.0.