Here's an old school effort. It's even disabled the "Undo" command, for better verisimilitude.
As far as the technical stuff goes, the coding is flawless. Although I did manage to conquer one of the puzzles in a way that I doubt the author imagined: you see, there is this magpie, and you have this gold key, and the magpie will insist on stealing it from you when you approach. But the magpie only reacts to the gold key if you are carrying it at the time of your approach, and the game allows you to throw stuff into other rooms.... (Doubtless, this workaround will have been "fixed" by now.)
The writing works, for what the game is. By its very nature, its writing is expected to be sparse. Nothing jumped out at me as being particularly brilliant or poetic, but then nothing made me want to cringe, either.
And now, the design.
The game operates on nostalgia. If you grew up in a time where Zork was unusual in its verbosity, you might remember games like this, with their sparse implementation and their rather excessive maps of insignificant rooms, not all of which have exits indicated. If you're not prepared to go back to any of that, you might want to give this one a miss; certainly, many of its "features" fall into the category of "things we don't do anymore because nobody likes them". But every so often ... and "Castle Adventure" is certainly short enough....
I'm usually the guy screaming about unnecessary "corridor" rooms, and this games has rather a lot of them. Strangely, I was not so annoyed as I otherwise might have been. I think it may be that the immersion was complete enough that I was back into the old 1980s mindset.
Grilled cheese on very soft, very white bread. Ovaltine.