Makes your brain hurt in a good way!
I discovered this gem courtesy of AppAdvice so was lucky enough to get it free, but I’d have happily paid full price. A simple premise that can be brain sweatingly hard to solve, but oh so satisfying when you do. The kind of satisfaction that makes you say “Oh, go on then, one more level” quickly followed by frustration as you see what you are up against this time. Love it!