Very intelligent game but...
Very brilliantly built game. It enhances your memory and gives a very good exercise to the brain. But after playing 261 levels on my iPhone 12 Pro, I observed that when this app is open its making a very low hissing sound repeating every second, which is almost not audible. I could hear it at night. It’s strange. I screen recorded to upload it but there’s no option to upload a video to the app review.