Global variable save/load. Can be used to save attempts and win counters for games. If a player try a level you can count up a value +1. When a player win a level you can count up another  value +1. Then you can grab the try value ex say the level has been played 10000 times worldwide but only 1000 has finish it. This means your level have a success rate of 1000/10000=10% of the total players worldwide. You can then see how difficult the level was worldwide.

You can have unlimited amount of rows and 30 counters in each row for you to play around with.