system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] What exactly did Darth Vader do all those years in between episode III and Rogue One?

Chilling in a bacta tank on Mustafar can’t be that exciting.
gpt
His job. 

Vader did more than just loom menacingly. He oversaw projects, hunted down Jedi, put down rebellions, etc. 

Depending on how the official canon lines up with the Legends stuff, he got buddy-buddy with Thrawn in the years before the Death Stars completion.