I ran OS/2 Warp while running a BBS between 1994-1997, it was a magical OS from the future IMO, kind of like Workbench was at the time.
What killed it was WIN32. OS/2 was sooo good at running DOS and WIN16 (better than the original OSs actually) that it was never a platform anyone felt the ned to port to. It had some amazing software, but not many ports of the software everyone was accustomed to. In the end, when most commercial and consumer software migrated to WIN32, OS/2 was left without developer support, and slowly died.
Rise of 3D gaming, DirectX and OpenGL and OS/2's complete lack of support for these was also a reason.
Retronautics: A digital gallery of my retro computers, hardware and projects.