The Staff of Karnath was the first title by 'Ulitmate Play the Game' I ever owned. At my school at least, Ultimate games were the premium titles that everyone wanted. They were more expensive than regular titles with big glossy boxes and packaging.
It's hard to explain, but Ultimate games had a certain 'quality' feel to them, a lot of my favourites being 3D isometric games like Karnath.
In Staff of Karnath you control Arthur Pendragon (who appeared in 2 other titles) around a haunted castle trying to collect 16 pieces before midnight so you can locate the staff and destroy it. Thinking back now they weren't a whole heap of rooms to explore but everything was presented in a very smart looking 3D for the time and I remember it being very difficult but immensely fun and replayable to walk around (for then!) realistic rooms.
There was no ingame music but adequate and typical Ultimate sound effects.
I recently watched a youtube video of someone obviously using cheats to complete the game (something I never managed) and amazingly you could do it in about 18 minutes! This truly was the era when games developers made the titles intentionally hard to drag out the gameplay for hours to cover up lack of content.
Staff of Karnath wasn't the best Ulitmate C64 title, that honour goes to Entombed for me but it's still a title i'd have in a personal classic c64 collection.