We all know that I don't have the willpower to learn languages, but… I'm currently in a "I'm totally learning Mandarin" phase, for like the 5th time probably, and I discovered one thing that is super helpful:
This tone training course! https://wordswing.com/cards/tone-training-course/
Actually, the whole Wordswing site is totally worth checking out, it's freemium but mostly free.
A lot of the other content is not meant for beginners, but the frequency-based spaced repetition thingie definitely works for me (I use it for practising writing, I only mark a word/character as good when I can actually write it), and the dialogues are above my level but still fun when I want to see some real sentences and maybe learn a word or two. (They are like LingQ, but less annoying/overwhelming, or like BliuBliu, but without the need to use a seperate dictionary / trust google translate.)
And for people who aren't beginners it's probably a lot of fun because there are text adventures designed specifically to learn Chinese? But I think at least one of them is paid. But still.