Mobile Keyboard Issues

Hi Natalie, I love the look of it, and I see what you are trying to do with the mechanics of it.

The reason the soft keyboard (on mobiles) is not opening is because it doesnt detect a standard TEXT INPUT FIELD. You need this "focussed" in order for the soft keyboard to appear on mobile devices.

You could maybe achieve this, whilst still retaining all you currently have done, by putting an invisible text field in place and when the user clicks on this, they will get the soft keyboard, and then you can trigger the appearance of your letters based on what they type.
Because the text field is invisible, whatever they actually type wont be visible.

that will probably work..... but honestly, I might advise coming up with a slightly different mechanic for your slide for all users (mobile and desktop)

At the moment its a little clunky, and it took me a while to realise I had to click on every box, but was still totally restricted to only typing the correct letter each time. It feels a bit pointless if I cant get it wrong :D

So, you could change it to use a standard text field at the bottom of the screen. This would be a place for them to type any letters they wanted. Simply copy the letters they type into the word they selected in your puzzle.

You can use a few variables and triggers which will check if they got it right or wrong, and also limit the number of letters they can enter.

I think that will feel much more fluid and intuitive, allow them to get it wrong, and also presents no issue for mobile users.

Just my two cents! :)