Forbidden Castle is a game set in a fantasy realm, and although it does not have a huge number of rooms, it's very hard. Unfortunately much of that difficulty is not related to the puzzles but to the parser and inaccuracies. It is written(or at least conceived) by Mercer Mayer, ostensibly the same Mercer Mayer who illustrated all those kids' books including the wonderful Great Brain series and even wrote some stuff(www.littlecritter.com for the whole deal.) While the fantasy elements that appear in his drawings appear here, and you rely on a lot of visual clues to complete the game, the Angelsoft parser causes awkwardness some times. The game's complexity outstrips it a bit so it's more likely to be remembered as scattered than eponymous. It's a pity because the descriptions really give nice foreshadowing and the game achieves a sort of internal logic although it tortures the player to find it.

I couldn't find any copies of the Apple rom image, but www.the-underdogs.org has this game available for download. I suspect there is little difference in the Apple to Windows port. After all how much can technology really soup up a text adventure?