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.
Was obsessed with Pokemon…
Got to Victory Road
Never found out how the hell to leave Victory Road
RIP in Peace
Did not beat a Pokemon game till Gen 4
2 - Copy of game was stolen from me…
3 - Skipped this generation due to being bullied for liking Pokemon
4 - Beat Diamond!