The boss fights in Kena got hard for me. When that happens, it teeters on not being any more fun. I know many like the challenge. I do too, but have a lower threshold. However, Kena has a lower difficulty and I just knocked it down for the boss fights. My enjoyment went back up. There's more to the game experience overall. I think I hit a wall with the game half way through. I think the story could've ended a little earlier.
Anyway, I think people know what they are getting into most of the time with game like those. Maybe not Kena
because it wasn't talked about enough. There are so many games available these days and to complain about a handful seems silly. Go play another game.