Finding Cheese Differences

In this game called 'Finding The Cheese' you need to find all the differences between the two seemingly identical pictures and you have limited time to do it. In the pictures we see Tom and Jerry in one of their standard poses. Differences are for example a smudge on the wall, one hole missing in the cheese, one of Jerry's mustaches being slightly longer etc. When the time runs out, the button 'show answers' appears and enables you to see all the differences. It is incredible how some obvious differences go unnoticed while they were just under your nose. The game is not too difficult, you play only with a mouse and even if you didn't solve one picture you can open and play the next one. The game is great for kids because it strengthens the power of observation and concentration. Still, I think that given time limit is too short and that it would be ideal if there were some hardness levels in settings.