Ok so, I've been looking for this game for a few years with no luck, but recently I tried posting on some forums and managed to find a couple other people who remembered about the game but still couldn't find it. The Description is this:

"you had an island map that you moved around in according to this dice that got thrown. You were a coloured dot that moved along the required amount and if you landed on a red chest you got either a gold bar, a silver bar, a key, got mugged or it was empty. You played against other computer dots that were different colours and they could rob you off all your things if they landed on you.
The aim of the game was to get the key then the wand then get ot the castle on the second part of the island. It was very basic and not hugely animated. Hope this helps "

Taken from this post.

"I was searching on Google for the very same game and decided it was called Merlin something too! Maybe Merlin's quest or Merlin's castle? It had poor graphics but was so good to play! The theme music was if I were a rich man! Have been searching and searching but am unable to find anything. "

Does anyone have any recollection of this? what it might be called or where it might be found? Google has failed me on this one so far.

By Merlin's beard! I have no idea. =/

Galahad and the Holy Grail ?
http://www.atarimania.com/game-atari-400-800-xl-xe-galahad-and-the-holy-grail_2138.html