Win3mu is a compatibility layer that uses 80286 CPU emulation. It loads 16-bit Windows executables and maps API calls onto the modern 32 or 64-bit Windows API. The software is a Windows 3.0 emulator. Games such as Solitaire and Minesweeper run, but no 3.0 programs work yet.
Its development was marked as postponed since December 2017 and then planned to be released as open-source. By late September 2018, it became open-source and its source code can be found below: