I was having a tough time years ago learning hiragana/katakana when someone recommended this Slime Forest Adventure game to me and I learned both in a few days. I have recently been getting my son to use it and I’d forgotten how great it was. Here is why!
**Different fonts**: it throws the kana at you using different fonts (some more stylised, some more basic). This helps you to read them in a real world environment.
**Kana grouped by similarity**: instead of learning in order like ラ, レ, リ, etc, you learn in groups that look similar, like ワ, ウ, ク. This helps you to distinguish between these right away.
**Uses SRS**: this game was doing SRS before Anki became so popular. I don’t need to explain why SRS is so great.
**Fun RPG**: it looks basic but it’s a serviceable RPG game. As for me, I just spent all my time in the first forest grinding battles but you can go as deep as you like.
Anyway, if you are learning kana then I highly recommend it. Apparently it does kanji too but I never used it. It also seems there is now a web version.