These demonstrations exhibit common programming techniques found in video games: 2D user interfaces inside a 3D graphics world; allowing movement of the camera in 3D space; interactivity, including controlling lighting in a room; basic gravitational physics; and collision detection between two objects. From these examples, you can extrapolate to make full-fledged video games such as traversing 3D mazes or shooting projectiles. From here, just add imagination.
Video games are one of the most pervasive applications of 3D graphics. Yet, most 3D games are limited to console devices such as Xbox and PlayStation, or PCs. At the same time, many people have access to a 3D-graphics-chip-capable device, either a smartphone, tablet, or a web browser on their desktop. This is a large audience, the type that likes to play a quick, enjoyable, artistic game—the kind of games produced with WebGL.
WebGL is cross platform, so we don't have to be concerned with Android versus...