I’m downloading Prime Climb right now. Exactly what I needed for our upcoming multiage maths trial. We are organising a range of low-floor high-ceiling tasks for students to opt into depending on their interests, this will value add to those activities. Thanks for sharing, Mark.
A suggestion I have for you is Skyscrapers. Mark Chubb has some free templates available here which you can download and print. The game is like Sudoku but uses coloured blocks to build the perspectives. There are many different levels for learners which get more difficult as the clues are removed. Good fun.