random thoughts: i think some games more execution focus. "harder" is more finesse in execution. some are more knowledge; getting better is arcane knowledge about the smallest details. most are some mix.

I look at what "being good" is, and what devs have to do to add a player-demanded "higher difficulty", and what players have to do beat it. What's fascinating is how the experience changes; Sometimes that means "breaking" the game (check-pointing and cheesing), sometimes not.