Leia and Luke crash land on Mimban, are arrested by stormtroopers, fall in with a pair of drunk aliens, escape, float on giant lily-pads, then chop off Darth Vader’s arm. This is the official 1978 novel sequel to Star Wars.
The film Star Wars was a huge gamble. No-one knew if it would be successful, so there were a few contingency plans to make the studio’s money back if it was a flop. One of these contingency plans was Splinter of the Mind’s Eye, a 1978 novel written by Alan Dean Foster. The idea was that this book could be the basis for a low-budget sequel film, re-using many of the sets and props from Star Wars, in the event that they needed to crank something out quick.
Alan Dean Foster, by the way, specialises in sci-fi novelizations, having written books based on Star Wars, Star Trek, Aliens, Terminator, and Transformers (not to mention quite a few original works). He wrote the novelization of Star Wars based on early versions of the script, so it notably differs from the film in a few key ways – Chewbacca gets his medal, for example! Foster was also contracted to write this sequel.
Splinter of the Mind’s Eye is pretty wacky. Luke and Leia crash land on a jungle planet and get up to some hi-jinks being chased around by stormtroopers while searching for a Force-amplifying crystal. As I mentioned earlier, at one point they are arrested and fall in with a couple of lovable drunks (who are later murdered by Darth Vader), they get in a bar brawl, fight monsters, float on lily pads, and have a grand finale lightsaber battle with Vader himself.
Both Leia and Luke fight him, but it’s Luke that manages to cut off Darth Vader’s arm. What is it with Star Wars and amputation? Sheesh. Vader falls into a pit, seemingly to his death. The book was published and was a huge success… but so was Star Wars, so it was never filmed, and its plot conveniently forgotten in favour of The Empire Strikes Back.