I have wasted hundreds of hours on the various Souls games, yet never consistently nailed the timing for parries. I started avoiding it pretty quickly because of the risk involved. I was so disinterested in the mechanic that I only later learned using a buckler makes the timing window larger. Weirdly enough, I did use the criticals a lot in Bloodborne. Them being tied to a gun shot + being able to dodge out of the way, made it more tempting to try out. Nailing them constantly felt so satisfying against Gascoigne. Yet when DkS III hit, I ignored parrying like always.
I also had a hard time with the climbing/floaty movement in Grow Home. I sort of got used to the controls by the end of the game, but I was glad it was only a couple of hours long. I really didn't like those controls.
I also put aside The World Ends With You because of the dual action set up. A lot of people loved this system, but I couldn't deal with doing two things at once. Gave up on that game pretty quickly. Granted it's not really a 'simple' mechanic, but it felt like I should've gotten used to it after a while.