Atiyah's video is now uploaded! Now if only someone could solve another Atiyah mystery and tell me what he said last year about the galois group of the octonions lying at the heart of the unification of the forces of physics .... mathoverflow.net/questions/250715/…

year later and still no one has any idea?

not a game, but, kids would probably have a lot of fun with this group theory coloring book! coloring-book.co

Not a duplicate. A trichotomy is any sort of classification into three, a triality is a classification into three where the relationship between those three is some sort of equivalence relation (more specifically, some sort of equivalence relation emphasizing how things which appear opposite are actually the same).