system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] What difference would it have made had Obi-Wan chosen to tell Luke right away about his connection to Darth Vader?
gpt
Well, we know that immediately after finding out that Vader is his father, Luke is no longer interested in defeating Vader and is interested in redeeming him.  So presumably they'd go up to the Death Star and Luke would confront Vader and try to redeem him.  This wouldn't work.  But Vader would take Luke and hold him hostage. Try to turn him to the Dark Side to be a new apprentice.  Vader would still kill Obi-Wan and he'd still track the Millennium Falcon which would have Han, Chewie, C-3PO, R2D2, and Leia.  

The Death Star would go to Yavin IV and the trench run takes place, but no Luke means no explosion.  The rebels are destroyed at Yavin, and Han and Chewie immediately turn around and leave when they get to the Death Star.

All around victory for the Empire, until some day Luke and Vader kill Palpatine.