I made my yeti version for the demo with 3D characters.
I downloaded the GPL version from gp32x file archive,
and examined the code of the little demo (game.c) to learn how to use it.
I modified the engine & tools to get 256 colors/texture (and not 256 for all)
and adapted the engine to use my 3D animated object format (MD2 like).
Orion, the author of the demo with the plane did something different, he use the
original engine (xith some own filters) and draw the plane on the rendered view
(ie 3D entities are not managed by the engine).
It takes a lot of time to do a game. The engine is not enough...except if you want
to do a maze game.
And as you certainly know, I begin a lot of projects, but finished only a small part
of them.
Thor