Thanks for the reply :), sadly enough I did not have enough time to playtest my game and the interface could have used more polish, notably the already filled tiles in the sudoku. I have found myself in situations where (at level 2-3,) I thought all elements were filled, but in reality some individual cells containing just one element did not have the marker. I fully agree that it is a (perhaps too) subtle change. That's definitely a point I will take for future jams ;)