It makes use of the following technologies
TFK and TFK:GE are both licensed under GNU General Public License, whose text can be found on next page. They are available for free (both as in free speech and in free beer).
The original idea came from Christian Clavet, who is not a developer and thus needed some help to setup a working game engine. Luc BRUANT, aka fullmetalcoder, offered his help and is currently lead developer of the engine while Christian take cares of the level editor.