Yeah back then there were no difficulty settings. Most people didn't even see the ending of a game. And if you did beat one of the impossible games, the ending would just be a screen that said "THANKS" or "A WINNER IS YOU" or pull some crazy stuff like Ghosts 'n' Goblins where it just makes you start over. Even the first Mario and the first Zelda just made you start over IN A HARDER MODE. And we liked it! And we had to walk to school 40 miles in the snow, uphill both ways!
But yeah, unlocking Invincibility in GoldenEye was IMPOSSIBLE. I was the only guy at my high school who could do it, and everybody else paid me to do it for them on their cartridges. They'd pay me in money, lunch, and sometimes fireworks for some reason. I think one guy even paid me in porno mags.
There are still some hard games. GoldenEye wasn't hard though. Just the bonus stuff was hard. Today's games have really easy campaign/story modes, and then add a bunch of really hard challenges just to appease us crazy folk. The older games were only for crazy folk. Sometimes when I look back at all those impossible games... I have no idea why I grew up liking games.