A
larger version of
Rubik's Cube, with a 4x4x4 arrangement of
cubelets.
The solution strategy is mostly to align the 4 center cubes on each face and the 2 middle cubes on each edge, and then proceed as if you had a normal Rubik's Cube. However, there are some ways in which it's possible to get a pair of middle edge pieces turned backward that aren't possible on the normal cube and require some other special moves to straighten them out.
Rubik never made an official 5x5x5 cube, on the thought that the corner cubies would fall out too easily, but there were some clone cubes made in this size, and indeed, the corner cubes fall out too easily.
Yep, this is also from the nrt