Enter a letter A/a and watch to see the background change colour depending on if the letter was a capital. This is using my own technique: Sprite based How can you do it? One method is just backpacking this sprite as it makes it really easy. You have to name the sprite all capital letters and have it positioned on an x position of 1 or anything that isn't zero (as long as you modify the code to match) But why does it work? It swaps the input character with the capital counterpart in a list with all capital letters. Then it checks if the x position of the sprite named exactly "ABCDEFGHIJKLMNOPQRSTUVWXYZ" is 1, if that's so, the input was a capital letter as the list wasn't changed.