i work on a free super mario 3D clone called Monkey World 3D, i use bge for that
here is the download-link:
http://platen-software.de/sebastian/mon ... 3d_v01.zip
Someone tried such a game some years ago (Supertux 3D)
see here: http://sourceforge.net/projects/supertux-3d/
but the developer stopped the development of this project some years later.
But i really don't want to stop this project, i have planned to make it as an free opensource game like supertuxkart.
My aim is to have an high-quality game with a lot of game-functions
in the first phase i set up some graphics and i want to make the movement better.
i also don't have a website now, that comes a bit later.
You play the blender-monkey suzanne (the model isn't the best, it is only a placeholder at the moment)
and you have to resque/save bigbuckbunny
it is a bit buggy at the moment, i added an debug mode, where you can fly (f1).
sometimes the player hangs when jumping, when this happens, go into debugmode and then out of it (press f1 two times)
here i have some screenshots: