Here are two puzzle games.
http://www.onemorelevel.com/game/loops_of_zen
http://www.onemorelevel.com/game/entangled
The second one is the sequel to the first one. The object of each game is to go as many levels as you can. There is no time limit and there is no score. They test your puzzle solving abilities. It's laid out in a grid and the grid gets larger as the grid squares get smaller. Right now I'm doing the second game and the grid is 12 by 12.