@speaktrap @dosnostalgic while I ain't got sources for it, I'd bet a lot of money that the reason Carmack preferred OpenGL was that it allowed him to code closer to the bare metal, which is great if, like Carmack, you're basically a space alien level supergenius.

For everyone else, a library like DX that distanced you from the hardware (especially with how diverse PC hardware had become at that point) and provided a common layer of abstraction between it and software made development of applications infinitely easier.

As for OS/2 I'd have to double check the timeline... But I'm fairly sure it dropped *after* windows 3.0.

... And either way it was codeveloped by the microshaft team and a lot of its code got used on windows too.