A nice 3D game with penguins.
It uses Tcl at least for its track configuration files. (maybe for more)
http://tuxracer.sourceforge.net/
the ?founding persons? of tuxracer went commercial( now defunct )
http://www.sunspire-studios.com
the oss version was continued by PPRacer http://freshmeat.net/redir/ppracer/53520/url_homepage/racer their first act of improvement was to rip out tcl ; pure vandalism!
someone has collected some info at: http://en.wikipedia.org/wiki/Tux_Racer