This is one of several adventures written by Dian Crayne. Dian's games were originally published by Norell Data Systems. Her article, on writing adventure games, appeared in PC magazine, Volume 2 Number 4, September 1983, pp.266-276
There are possibly two different versions of the game. The 1983 version, sold by Norell, was commonly referred to as just Elsinore. The archived 1992 version is called Castle Elsinore and invites the user to register the game as shareware.
[+] Users currently playing this game
Unlike other Dian Crayne adventures, this one is a bit less driven by a transposition of Colossal Cave puzzles, and it is slightly more reminiscent of Zork. Although not bad, it falls short of expectations, being a very run-of-the-mill treasure quest with less atmosphere than other Temple Software games and more annoyances (like random fights and the pointless mazes).
There a few bugs here. Items dropped in the castle are listed as being in the crotch of the tree if you visit that location although you can't take them. The SWEEP and CLEAN commands elicit a blank parser response. The Shopkeeper is described as a woman but as a man if examined. Trees examined in the garden lead to the description of the trees in the forest. Examining the cauldron gives a description of the witches. On the whole though this was an enjoyable game and the bugs don't really impinge on game play other than as an annoyance.