Cogs is brilliant. Cogs is beautiful. Cogs has style. Cogs will put your mental powers to the ultimate test, and best of all it's only $.99. Remember those slider puzzles you used to get in your cereal boxes back in the 70's and 80's – usually a 3x3 or 4x4 grid of squares with one square missing and you had to slide the pieces around to make a picture or put numbers in order or solve something. It was the precursor to Rubik's Cube.