Has anyone heard of this game, Slashcards?
I have had the pleasure to stumble over it while searching for games on itch and it is quite an amazing one! The author has expanded the game as far as learning a few hundred vocab words and quite a bunch of Kanji. Also, the game supports multiplayer gameplay and has a couple of fun games for grinding new words you’ve learned.
BUG: If you wish to jump over the entire Hiragana forest (like I wanted and did hehehe) just go to the far right of the forest and walk around it. It’s as simple as that, and then you can go and do all the fun vocab monsters and kanji !
Video to show how to avoid the Kana Forest: https://youtu.be/IEez2CY5smY (jump to 03:04)
I have been playing it for a week and I must say that I have fallen in love with it.