Pretty sure SimTower works in Windows 9x.
And yep, I was right.
From the Wiki:
"WinG out-of-the-box support (i.e. as a separate API to Win32) was dropped in Windows 98 Second Edition (which integrated DirectX 6), as it did absolutely nothing but pass through to the Win32 APIs that it was wrapping. WinG DLLs were sometimes distributed with an application, at which point it merely became a matter of copying the files wing.dll, wing32.dll, wingde.dll, wingdib.drv and wngpal.wnd to the system32 directory to regain system-wide support."
So absolutely 0 reason to have Windows before 9x for gaming.