Creating a viable game engine would require a lot of investment for maintenance (ie: answering people's questions, fixing bugs, keeping compatibility up to date etc...) it's not just about programming the engine. I think it would require you to either hire people or make the engine open source. But I think there is already too much competition rightnow for pure 3D engines. But I also think that there is a great field of opportunities for middleware "on the side", stuff to help artist or to smooth out the creation pipeline, so as other have suggested I will tell you to find an original idea, something that coud become complementary of ogre or unity or udk. Recently DrPetters released SFXR, and I think there is a lot of room for improvement. So far it is the only non-professional tol for sound creation (well the only one that I know) and I think there could be a lot more options (like for examlpe mixing several sounds in the editor, a timeline, changing the waveform of preexisting sounds etc...) using audacity +sfxr is a bit clunky.