Chroma additional levels: The 12 original ones of Engima
Chroma is an abstract puzzle game. A variety of colourful shapes are arranged in a series of increasingly complex patterns, forming fiendish traps that must be disarmed and mysterious puzzles that must be manipulated in order to give up their subtle secrets. Initially so straightforward that anyone can pick it up and begin to play, yet gradually becoming difficult enough to tax even the brightest of minds.
More information on Chroma can be retrieved at http://www.level7.org.uk/chroma/
These 12 levels were originally designed for the game Enigma by somebody who wants to remain anonymous and thus donated the levels to the public domain.
More information on Enigma can be retrieved at http://www.chiark.greenend.org.uk/~sgtatham/enigma/