One activity I though I might do when I retired was learn a foreign language. So I've started trying to learn Japanese, for the moment using apps on my iPad rather than evening classes. Evening classes were out of course during the time of Covid.
Japanese as a language presents some distinct challenges. Sensible languages have just one writing systems, which in good languages is phonetic so you can look at a word and know how it's said. So far I've encountered three different writing systems the Japanese use - Hiragana which is a phonetic system for native Japanese words, Katakana which is a parallel phonetic system for non-Japanese words, and Kanji which are Chinese characters (Kanji comes from Hanzi which is literally Chinese characters) the Japanese use just to make life interesting.
Even more interesting is that the Kanji characters can be pronounced in multiple ways, one way seemingly derived from the Chinese pronunciation, another way from the Japanese word that the Japanese borrowed the Chinese character to represent. There is a system of modifiers which can be applied to the Hiragana and Katakana to get different sounds.
So far I've used the Hiragana Quest app to learn Hiragana and Katakana. This app does a great job of suggesting stories to help one remember the Hiragana and Katakana symbols, and also giving a little background to the writing systems. However the app is limited to learning the writing system and the sounds, no further.
I'm trying Drops to learn words. Drops has a great drilling system, and claims you can learn a language on 5 minutes a day. For Japanese at least there's no background given, or no explanation of the different sounds for a given Kanji character. So Drops is great for what it is, but on its own it's not enough.