My two:
Very cliché, I played Ocarina of Time a ton as a child, have memories of playing it both on N64 as a wee child and on game cube as a less small child. Never got past water temple even with the game guide.
Yu-Gi-Oh forbidden memories. Played the crap out of that game on play station, constantly playing on free play praying for the cards I would need to get further. I was never able to beat more than 1-2 of the high mages. Watching speed runs on the game it turns out I was never ever going to beat that game as a kid. The final 6 are just disgustingly brutal.
I’m not a gamer, but I got really into ff8 in high school. I tried a bunch of other rpg games back then too, but I could never beat them. I always got to a point where I wasn’t strong enough to win a battle but didn’t want to go back and grind, so I’d eventually give them up.
…not sure what that says about me as a person.