I am building a calm, serious English vocabulary learning application for mostly adult, motivated individuals. The opposite experience to Duolingo. No dancing mascots or childish sound effects. I am betting on attracting young professionals, academics, white-collar types that like books, language and the experience of a white page with classic, black typography.
Strangely, through iterative prototyping, the app evolved into something that my testers (and teachers) are calling... a game. I see it as a good thing, and I am adapting this language. The free version is about 'play,' and the paid version is about 'study'.
Reach out if you would like to chat!