S.C.R. claims this game is a high quality adventure aimed at master player and novice alike. I have no quarrel with that, Castle Blackstar is very good indeed.
Having "woken from a sleep troubled by strange dreams", i.e. with a hangover, it seems that you have rashly promised the tall, willowy, blonde Lady Artemis that you will enter Castle Blackstar to reclaim an orb. In return she will let you keep anything else that you may find. Not much of a bargain, I grant you, but that's blondes for you!
The game is text only and has a vocabulary of over 200 words of which only a few are known to you to begin with. Response time is good and you may use short sentences like "TAKE LAMP AND LIGHT IT" or simple verb and noun combinations. As you search you face many and varied dangers, not least of which is getting lost if you do not keep a careful note. If you are killed, and you certainly will be, you are reincarnated outside the castle.
Castle Blackstar uses almost all available memory to provide maximum play potential and should offer long-term interest. Highly recommended!