A landscape generator.
The description and the code are available under the following licenses:
The interface GL.i3 is available under the free license covering Modula 3. It may not be compatible with the GPL, so you shouldn't distribute linked binaries containing it and GPL code. Distributing source is OK.
The interface GLU.i3 is available under GPL2, or later.
The interface Glut.i3 has its own copyright notice and license, q.v.