While NT OS/2 effort started earlier, Windows 3.0 was apparently an unsanctioned originally rogue effort started by one developer, initially masquerading as update to "Windows-as-Embedded-Runtime" that multiple graphical products were shipping with, not just Microsoft's

Even when marketing people etc. got enthused enough that the project got official support and release, it was not expected to be such a hit of a release early on and expectation was that OS/2 effort would continue, if perhaps with a different kernel.