Cool!
Currently in the challenge stage: Once you you provide an answer whether correct or incorrect, you must back out and begin again to receive another challenge. It would be great that if once you have your answer, it continued to cycle through a a pre-selected amount of challenges ( 5, 10, 20 etc. ).
In this way, it would provide an exercise of mental stamina. Perhaps this option can configured in the settings, along with the option that allows for the setting of time intervals for the numbers.
Response from developer
Thank you for your suggestion again! (For other readers: the previous one was about adding sound effects, which I did later on.) If you mean you’d like to avoid bothering to think of which button to tap on to challenge the same stage, I’ll think about highlighting the button rather than adding such an option as you wrote.








