8 moves
Four faces keep only their centre colour. The other two stay solid.
Finished patternStart from a solved cube. On a scrambled one these turns make nothing but a mess.
Run the same algorithm 2 times in total and the cube is solved again.
Each letter is one face, turned a quarter turn clockwise as you look straight at it. An apostrophe means anticlockwise, and 2 means a half turn.