I could install Windows Me.
I used that until 2019.
I see, thanks for the reference. I'm a single developer and even though I could put some extra effort and likely step back back to OpenGL 3.0 - 3.1 (downwriting some of the render features), this would be an inefficient use of time for my effort. OpenGL 3.3 given me certain conveniences which I would prefer to be there in the engine and I could dedicate my limited development time into other areas (e.g. better AI and better SFX). :-)