Quote Originally Posted by masonwheeler View Post
Can you think of any examples to the contrary?
Unity3D and the Unreal Engine. Afaik, the variety of games I've seen made with these is large. An engine is an engine, regardless if it comes in the form of a library or just compiled into your project (which is most likely course for pgdce), or if it comes with a nice editor for everything. Also, your solution is not an 80% solution, or even close to that. Starting from scratch will make it easier to make the engine cross-platform and modular (being able to use different rendering/audio systems and what not), instead of having to do major refactoring to an existing project. Which in my opinion will end up as more work.

As for why anyone would want to choose between DX and OpenGL, because it gives choice. Also, even if there is no DX support, making the rendering system modular is still a wise decision.