Can be played cross-platform. Must be developed on a Macintosh. Can be developed on any medium to high performance computer. Content must be real. Content must be modeled.
Final result is photographically detailed.
No modeling is required. Must convert everything into points, shapes, surfaces, and locations. Hands-on development with photographic equipment and relatively straightforward software. Must learn how to use complex CAD or VR software for complex productions. Resulting scenes can be very large because of digitized image quality.