Instead of a streak
A reminder at the moment a repeat has come due
Not every day, but exactly when a word starts being forgotten.
Why no games
In rigorous studies games affect neither the wish to learn nor how regularly people study
Of 0.49 across all studies, 0.29 remains in randomised ones — and only on knowledge. Motivation 0.13 and behaviour 0.12: no effect found.
Sailer, M., & Homner, L. (2020). The gamification of learning: A meta-analysis. Educational Psychology Review, 32, 77–112