All of us have them. The games that, no matter if we played them every day for ten years like some martial arts student, we will NEVER beat. And so, time to cheat!!
Just a few examples from me:
Undead Line (ANY VERSION) and Elemental Master (Genesis) - DAMN!! Hard as F#$R$@!
Lightning Force (Genesis) - Couldn't get past 2 or 3 stages as a teen, and can't even get past one now.
Bucky O'Hare (NES) - NOT happening.
Super C (NES) - Though I can legitimately beat the first one no problem . . .
What are some of yours?