Also, there was a transitionary predecessor to DirectX that some (primarily edutainment) games released for Windows 3.1 (and for a short while into early Windows 95) called WinG. So far as I know most of the WinG games also relied on Win32s to get access to 32-bit code, but I don't know if Win32s was a requirement to build a WinG game or if there were 16-bit games for that platform too.