Making flash card games accessible

Hi all,

I'd REALLY like to include a flash card game in my eLearning template. They are fairly easy to create if it wasn't for one thing: Accessibility

How do you communicate to a blind person that they've matched the right pair of cards - continuously on a slide with - say - 10 cards? I'm guessing I'd be using a bunch of variables and/or state changes, checkmarks that appear etc. and maybe communicate to the user via off-slide text that is initially hidden, but before I start reinventing the wheel, I'd like to know if anyone has tried this out? Does anyone have a flash card game in their library that's completely WCAG 2.1 compliant? 

Best regards and have a great weekend!

Michael