Oldest GUI application that still runs on Windows 11

In a quest to discover the oldest graphical user interface (GUI) application that still runs on Windows 11 without modifications or emulation, a reporter delved into the depths of historical Windows versions available on the Internet Archive. The reporter initially expected to find an impressively ancient program, given Windows' excellent backward compatibility, but discovered that running 16-bit Windows programs directly on Windows 11 is not possible due to the absence of the 16-bit Windows protected mode emulator (NTVDM) in 64-bit Windows.

The reporter remembered a previous question posed on an anonymous forum, which led them to Win32s and the game FREECELL.EXE. This classic game, dated 22nd February 1993, successfully ran on the latest version of Windows 11, making it a 33 years and 8 months old application. Intrigued by the discovery, the reporter decided to dig deeper and found early NT 3.1 pre-release versions, but faced compatibility issues due to incompatibility with modern executable formats and API changes.

However, a promising lead emerged with CDPLAYER.EXE from Build 347 on 16th November 1992. The reporter found that this music player application was compatible with Windows 11, as it used the system's crtdll.dll, which is still present in the Windows 11 SysWOW64 directory. By using a small DLL (cdemu.dll) to emulate a CD-ROM drive, the reporter managed to get CDPLAYER.EXE to play audio, showcasing a very cool program almost 34 years old.

The reporter also mentioned that running 16-bit programs on Windows 11 can be achieved using otvdm, but this approach felt like cheating. However, they included a fully playable version of REVERSI.EXE, originally released on 15th November 1985, running on Windows 1.01 as a testament to the power of otvdm. Despite the unconventional methods, the reporter found the experience of running these ancient GUI applications on modern Windows compelling and decided to share their findings in this report.