If you want, DM me on https://twitter.com/LukasPlatinsky and I can send you a link to try a POC for a language-learning text adventure game. The main concept is to tell a story through conversations with NPC chatbots. Would be curious to hear feedback or any suggestions on how it could be graded to increase the complexity of the language over time.

It's briefly mentioned on the site as well: https://hn.lingually.ai/#two