Rubber Ninjas uses the SDL, SDL_ttf, SDL_mixer, SDL_image, libogg, libvorbis and freetype2 libraries.

These libraries are free software but Rubber Ninjas is not.

SDL, SDL_ttf, SDL_mixer and SDL_image libraries by Sam Lantinga (available at libsdl.org) are used under the Gnu Lesser General Public License 2.1 license provided in the "LGPL.txt" file. You can get the latest version of SDL and its source code at libsdl.org

libogg and libvorbis libraries by the Xiph.Org Foundation are used under the terms provided in the "Ogg Vorbis License.txt"

Freetype2 by the The FreeType Project (www.freetype.org) used under the terms provided in the "FTL.txt"