I would vote for targeting 10.13 or later. Our lab also have many Macs that are stranded on 10.13 as 10.14 does not support their Radeon GPUs (even though they are far more powerful than some integrated Intel GPUs that are supported by 10.14). With 10.14 Mojave Apple has deprecated OpenGL. In my experience, an OpenGL application on 10.14 can not set the “NSRequiresAquaSystemAppearance” to “false”. This means that OpenGL applications can not automatically take advantage of the Mojave Dark Mode. I think this reflects a difference in the Mojave layer manager. A bigger issue is that OpenGL code that works fine on 10.14 when built against the 10.13 SDK fails when built against the 10.14 SDK. This has been well documented, and you can find hacks for this with a web search. Given that OpenGL is deprecated, it is unlikely Apple will fix the OpenGL-specific bugs introduced with the 10.14 SDK. It is unfortunate that one of the worlds most valuable companies does not want to devote the resources for this open standard. Pragmatically, 10.13 appears to be the last version that treats OpenGL as a first class citizen.