The Castle of King Lucius is an early role-playing ZZT world (or 'module', as Eli Tremblay himself calls it), released around the same time as Ezanya. It's a short game where you explore the castle in question and-that's it. It feels like there should be more lore on why you're visiting this castle and who King Lucius is, but there is none. Not even a scroll at the start of the game!
It starts out strong, with a good-looking title screen and twinkling-star animations. The game then makes you explore the different floors of the castle, with the king residing on the topmost and final one. Items needed for the quest are found on different floors, so make sure you explore all of them! The game is in general well constructed, with different floors clearly representing different parts of a castle and using colours effectively. The final few floors have some good-looking visual effects as well. There are also NPCs and artefacts to interact with, some having their own backstory (which again makes the lack of information on King Lucius puzzling). There is also a red herring at one point which is neat but obvious at the same time. Where it trips up, though, is in an excessive use of slimes and scarce ammo. Make sure to conserve ammo as you'll need every round of it, and not just for the slimes! To the author's credit, the slimes do not spread at an unreasonable rate. Even then, the slimes will most likely force you to save and reload a few times before you figure out how best to outrun or stop them while preserving ammo. All this in a mostly dark castle. The game, fortunately, is quite generous with torches and health (in the form of gems).
But these are issues that can be overcome with practice or trial-and-error. More serious is the fact that if you don't visit the castle in a particular order you can be locked out of winning the game due to how the encounter with King Lucius is programmed. All I'll say is start from the bottom to avoid this problem.
I do recommend this game. Given the date at which it was published it's polished and engaging. In 1992 the forced trial-and-error bits and ammo hoarding would have been acceptable, and the issue I bring up doesn't render the game completely unwinnable. However these issues, and gaps in backstory, place it below a more complete contemporary like Ezanya.
Tremblay would release one more ZZT world- a demo for an RPG, the Realm of Dammak, which shows much promise and is more ambitious graphically and gameplay-wise. I also recommend it.