https://m.slashdot.org/story/341792Apple Deprecates OpenGL and OpenCL in macOS 10.14 Mojave
https://developer.apple.com/macos/whats-new/Deprecation of OpenGL and OpenCL
Apps built using OpenGL and OpenCL will continue to run in macOS 10.14, but these legacy technologies are deprecated in macOS 10.14. Games and graphics-intensive apps that use OpenGL should now adopt Metal. Similarly, apps that use OpenCL for computational tasks should now adopt Metal and Metal Performance Shaders.
Metal is designed from the ground up to provide the best access to the modern GPUs on iOS, macOS, and tvOS devices. Metal avoids the overhead inherent in legacy technologies and exposes the latest graphics processing functionality. Unified support for graphics and compute in Metal lets your apps efficiently utilize the latest rendering techniques. For information about developing apps and games using Metal, see the developer documentation for Metal, Metal Performance Shaders, and MetalKit. For information about migrating OpenGL code to Metal, see Mixing Metal and OpenGL Rendering in a View.
Things like this raise the question if a client architecture based on an actively supported open source engine might be beneficial, as platform independence issues could be farmed out to the engine developers instead of being an additional burden on the game developers...
https://godotengine.org/