A post on blog.enlyth.com asks a narrow question: what is the oldest GUI application that still runs on Windows 11 with no modifications and no emulation. Sixteen-bit Windows programs are out, since 64-bit Windows has no NTVDM, so the search starts with the early NT era.

The first answer came from Win32s: FREECELL.EXE, dated 22-Feb-93, is playable on current Windows 11. Digging further through NT 3.1 pre-release builds on the Internet Archive turned up older candidates that failed. The 1991 builds use a draft PE format modern Windows will not load, and builds up to mid-1992 assumed cdecl instead of stdcall for Windows API calls, so arguments get removed twice and the program crashes.

The winner is CDPLAYER.EXE from Build 347, linked 16-Nov-1992. Other programs in that build crash in their bundled C runtime, but CDPLAYER uses the system crtdll.dll, which Windows 11 still ships in SysWOW64. With a small cdemu.dll to fake a CD-ROM drive, it plays audio.…