What about this wagotabi videogame? I barely tried it, not my cup of tea, but maybe for kids…
I personally tried it but got bored after a while because it’s extremely beginner level, nevertheless it’s very well-made and i could see it being very helpful for kids/beginners (it also has reviews in it with a simple SRS system)
I had never heard of Marugoto Online, they even offer practice and kanji! Thank you for the suggestion!