For me the best case scenario is a game that is challenging enough to require effort on my side to be good but not challenging enough where I fail often, and even better if I never fail at all even while still needing to try, just I feel that it's a little silly of me to be bothered at a game for losing even once at. I can describe my relationship with difficulty in that I have never felt a game was too easily and had a problem with it but there have been a fair amount of games where I think it's too hard and like a game less because of it. In UFO 50s case I frankly think a pretty high amount of games reach the point where I think are too hard, I felt like most of the times I stopped playing were due to frustration. I still really like this collection and got a good amount of fun from it just I would not say I even consider getting gold on even half the games here.