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.
Majoras mask
Oh I didn’t play that until i was an adult, but that sounds like a nightmare as a kid without guides…
I was like 10 it was tough as nails lol barely made it anywhere
I had no guides, but was about 14. A lot of trial and error
Oh man I bet! Especially for the ones that had to be done on day 3 with no speed up mechanic.