Well, a max move count would prevent spamming to win, so you could eliminate pause and give a more generous timer. As it is, for me anyway, the timer isn't nearly enough time to think through the puzzles! There is another problem then - if I recall correctly, the puzzles are static and you can retry them any time. In theory you could think about them forever, then try them again after failing. One way to approch this is to make the time requiremeent soft - give a set amount of score for the puzzle, that counts down to 0 as time passes. When it hits 0, you just don't score any points for that puzzle. Sort of similar to the time pressure system used in escape simulator.