This news from Cyrus64 :

GreenGiant emailed to say that he has launched the Dreamcast section of his website, and released 3 demos to go with it!

First up is Pong, a single-player version of the game for the Dreamcast. It has basic 2D graphics and music, and displays a pong logo on the visual memory unit.

Secondly, we have a ‘simple 3d engine’. First you input a 2d profile using the control pad, and subsequently a wireframe object is generated from this and displayed. A volume sweep is used to transform the profile into a 3D object.
You can then perform such tasks as translating, rotating and scaling the object, aswell as changing its perspective.

Finally, there is OpenGL Objectorium. The program displays a spinning swirly thing in the background on top of which it shows 1 of 5 textured objects. There is also music in this demo. Control pad buttons A and B cycle through the objects. Each object spins in the centre of the screen when it has been selected.

Check out his site Here