A game which is hard to categorise, hence this thread, but one which can be played casually so I have also mentioned it there.
For me this is most fulfilling game in several years, fully deserving all the awards it has gathered so far, and the creator is nothing short of a genius!
You may like to look at his website and blog
https://www.hempuli.com/After over six months I have completed 213 levels and there must be at least another 10 (some levels are hidden until earlier ones are completed, and even then it can be part of one level to find another...) - several took more than 24 hrs head-scratching and a couple of times I left it for a week or so: I must admit to using a walkthrough on a handful of occasions (although that rather defeats the point), but more often I would wake up with an idea which worked or at least generated another idea - great fun and very satisfying!
I found one particular walkthrough which provides a useful overview of the game and a series of hints rather than giving the whole show away
https://www.keyofw.com/baba-is-hint/overworld.