I’m building a blackjack card counting tool for people to learn how to count and how to identify games that are winnable. It is designed to take a completely novice to an advanced, winning card counter, using a Duolingo like approach - mastery based learning across sequential modules. Minus the ads and dark patterns.

That sounds super cool! When you say Duolingo do you mean spaced repetition? If yes, have you identified what type of spaced repetition approach you will take?