Wine is an implementation of the Windows API on top of X and Unix. It does not require Microsoft Windows, but can use native Windows DLLs if they are available. It provides both a development toolkit for porting Windows source code to Unix as well as a program loader, allowing many unmodified Windows programs to run on x86-based Unixes.
minor feature: Vulkan shader compilation using the new vkd3d-shader library. USER32 library converted to PE. Console no longer requires the curses library. Support for display modes with various orientations. A number of syntax in the WIDL compiler. Non-recursive makefiles. Various.