Krull for the Atari 2600 is based on the movie of the same name. It was released late in 1983 and video game sales were plummeting at this time so Krull probably didn’t sell as well as it could have. For a game based on a movie, it isn’t as terrible as most.
Krull the movie is a cult classic and is sort of a fantasy/sci-fi hybrid. While it doesn’t have quite the name recognition of say Tron or Star Wars or probably even Willow, it was a decent movie for those that like that sort of thing. The game follows the plot of the movie pretty closely and consists of four different parts matching up with different parts of the movie. While the game received mixed reviews, it’s above average for a movie license and is worth a try, particularly if you are a fan of the movie.
There aren’t any sequels, remakes or rereleases of this game that I know of so you will have to play on an original Atari 2600 or use emulation. The only other game based on Krull was an arcade game by Gottlieb but it is unrelated to the Atari 2600 game other than also being based on the movie.