But in the Game ...
When they sat down to make the NES game in the early 1990s, they decided they were going to get rid of all this depressing shit and write the movie Lucas should have made. So, instead of getting tossed around like a child, Luke arrives at Cloud City to greet Darth Vader with a howling explosion of furious ass-whoop. He sprints down the spindly chasm bridge and pummels the Sith Lord like a jazz drummer cracking open a pinata with a pair of nightsticks, until Vader simply collapses under the weight of his own embarrassing failure and falls off the fucking bridge.
He just shit in his robot suit, and now he has to smell it all the way down.
However, the greater departure from the film's storyline comes after Luke beats Vader in 10 seconds like he was late for a meeting. Once Vader is defeated and sent hurtling down the inexplicable sky abyss/twinkling future slide, he delivers this message:
"Next time, Skywalker ... NEXT TIME!"
That's it -- a generic bad guy rant about "meeting again" spat out by Shredder, Skeletor, and countless Scooby-Doo villains over the years, with absolutely no mention of being Luke's father. The most iconic moment of the entire film (and one of the most famous moments in cinema history) is just kind of skipped right over for no discernible reason. To be fair, we understand the omission -- Vader would probably rather divulge that information while looking a bit more dignified and powerful, instead of screaming it over his shoulder while rocketing headfirst down a giant elevator shaft.