What do you mean I can't include Cuphead on a list for kids? Alright, it isn't really suitable for younger kids, but I still think it is OK for older ones. I agree that it isn't an easy game. Having put in numerous hours and still not really gotten anywhere, I can attest to its difficulty, but as with anything, practice makes perfect and, yes, I think older kids can get to grips with it.
The animation in the game is amusing and very well done, and if kids watch retro cartoons on certain kid's TV channels, there is nothing really that they haven't seen before.
Cuphead is currently available on Steam for PC and also available on Xbox One.