Great job! Coincidentally I was talking to my son today about needing to speed up his reaction time with simple multiplication. If there was an option to put this game into a mode where it asked multiplication questions only that would fit the bill perfectly. Taking this further, being able to choose addition only, or addition/subtraction only, or subtraction with/without negatives would make it playable by a lot of different ages. Also, I'd pay for an add-free version.