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.
The story I heard was that the game would crash on the standard N64 hardware, but it worked fine with the extra memory that the dev kit ran. They couldn’t figure out why the extra memory made a difference since it wasn’t actually using the full amount anyway, but including the expansion pak was an easy solution, so that’s what they did.