Comment by dpkrjb

Several of my friends and family members are playing Countable, which is completely ad-free on iOS (https://apps.apple.com/gb/app/countable-daily-numbers-game/i...) and Android (https://play.google.com/store/apps/details?id=com.pibbon.cou...).

Full disclosure: I developed this app during Christmas '22 with the idea of offering only one challenging new puzzle/level each day. I believe that the focus on the level of difficulty makes a huge difference.