Duolingo is terrible†, but proper gamification combined w/ LLMs for real conversations could be an incredible learning tool. (I might build this if no one else does.)
†It can be useful for going from absolute 0 to epsilon, just to kind of get familiar with the language, but if you're using it more than like 2 weeks, you're seriously wasting your time (vs. reading material in the target language, watching TV in target language, trying to talk w/ people in target language). Anki, too, can be a trap that feels like learning but isn't, really, in my experience.
†It can be useful for going from absolute 0 to epsilon, just to kind of get familiar with the language, but if you're using it more than like 2 weeks, you're seriously wasting your time (vs. reading material in the target language, watching TV in target language, trying to talk w/ people in target language). Anki, too, can be a trap that feels like learning but isn't, really, in my experience.