Is this possible?

HI everyone,

I'm just learning Storyline (and I'm just getting back to doing elearning again, hence my absence from the community), and what I would like to be able to do is too advanced for me right now. I'm not asking for someone to do this for me. It's more that I'm curious whether it is possible to do this in Storyline in a reasonable amount of time. What I would like to do is to create a specialized keyboard that allows students to enter special characters into a text box. Someone had already made a suggestion about how to do this, and it gave me a lot of ideas about what I could do. However, the problem with that method was that it was very easy for students to guess what the correct answer might be: only the correct letter was clickable, and only the correct letter would get entered into the text box. I imagine I could get around the only the correct letter was clickable problem by putting a clickable transparent object over the entire slide, and then bringing the correct letters to the front. However, I can't figure out if there is a way for the student to see what letters they had already entered into the textbox, even if those are wrong. I have a feeling that this could only be done with layers that imagine every possible combination of letters, which would be impossible give how many choices there could be. However, I'm curious whether this the case. I saw Phil Mayer's calculator example on his Periodic Table Community Showcase, and that looked like a similar problem to the one I'm describing. Anyways, I've attached a mockup that shows what I'm trying to do (I didn't care that much for colour coordination or the graphics for buttons, so it doesn't look all that good). As I said, I'm just trying to get a sense of whether this is something I can eventually aspire to or whether I should think of something else.