This guy is writing a Win16 emulator

Brad Robinson is developing a 16-bit Windows emulator to run old Windows 3 programs on modern 64-bit Windows systems, since 16-bit apps are incompatible with Windows x64. His project aims to emulate the CPU and map 16-bit Windows API calls to their 64-bit equivalents, allowing legacy programs to run like native applications without full hardware virtualization. So far, he has a proof of concept that runs simple 16-bit programs, and he plans to share the development journey through a series of articles. The project serves both as a challenging learning experience and a potential solution for running vintage Windows software.