3D slider puzzle for children, but surprisingly tricky even for adults. Helps learn 3D problem solving skills. Similar in concept to the 2D "fifteen" slider puzzle. Written in C++, this code compiles and runs on both OS-X and Linux. Now, improved function on laptops; runs on OS-X Retina displays too. Too easy, you say? Try Rufas' Cube, my 3x3x3 big brother.
There is also an Ada version available called SevenAda.
Choice of two easy build systems that allow anyone with OS-X or Linux and GCC to recompile; but first try the delivered exes.
Mac OS-X or Linux with graphics card that supports OpenGL v 3.3