This game is challenging. I purchased the ad-free version to support the development and ads are annoying..
My biggest suggestions are
1) please add a hint function. When I get stuck, my only option is to become frustrated and quit the game.
2) it needs a pause button because as it is presently, if the phone or doorbell rings, there is no way to stop the timer from running.
3) the app needs a "save game" function because every time I have to quit the game, I have to start all over.
Once these very reasonable modifications are made, I'll be happy to re-write my review.