I've made a set of classes to facilitate the use of ZenGL. It's called EasyZenGL. It proposes a TGame class to derive. Here you can download the library with Andru's example 1 to 5 translated into EasyZenGL, and a game demo, using Chipmunk physics integrated into TSprite class.

http://consume.o2switch.net/EasyZenGL.zip

Note : projects are in Lazarus format.